ECHANICAL 
DRAWING 


SCHOOLS 


C.C.LEEDS 


D.VAJV  NOSTRAND  COMPANY 


PUBLISHERS 


MEW  YORK 


LIBRARY 

OF    I  II I 

UNIVERSITY  OF  CALIFORNIA. 


Class 


The  D.  Van  Nostrand  Company 

intend  this  book  to  be  sold  to  the  Public 
at  the  advertised  price,  and  supply  it  to 
the  Trade  on  terms  which  will  not  allow 
of  reduction. 


Carnegie  {Technical  Schools  £cyt  Boohs 

MECHANICAL  DRAWING 

FOR 

TRADE    SCHOOLS 

BY 

CHARLES  C.   LEEDS 

Assistant  to  Head  of  School  for 

Apprentices  and  Journeymen 

Carnegie  Technical  Schools 


HIGH-SCHOOL    EDITION 


OF   THE 

UNIVERSITY 

OF 


NEW  YORK 

D.   VAN  NOSTRAND  COMPANY 

1908 


& 


COPYRIGHT,   1908 
BY 

D.  VAN  NOSTRAND  COMPANY 


THE 

VAN   NOSTRAND   PRESS 
NEW  YORK 


OF  THE 

UNIVERSITY 

OF 


PREFACE. 


THE  purpose  of  this  book  is  twofold:  To  prepare  High-school 
students  to  pass  the  examinations  required  for  admission  to  Technical 
Schools,  and  to  enable  the  High-school  graduate  to  earn  his  living 
as  a  tracer  or  detail  draftsman. 

The  author's  conviction  that  the  use  of  models  serves  to  develop 
copyists  and  often  tends  to  stunt  or  destroy  a  draftsman's  creative 
faculties,  has  led  him  to  discard  entirely  the  use  of  models  in  teaching 
Mechanical  Drawing,  and  he  feels  that  it  will  be  obvious,  even  to  the 
casual  observer,  that  when  a  student  has  been  given  a  model  of  his 
subject  for  the  drawing  lesson,  little  or  no  effort  will  be  required  from 
his  imagination. 

The  model  stands  before  his  eyes,  complete;  no  effort  on  his  part 
is  necessary.  When  the  student,  however,  is  given  a  blue-print  or 
drawing  of  the  subject,  difficulties  arise  at  every  step.  In  order  to  under- 
stand the  meaning  of  the  views  shown,  he  has  to  study  the  subject  care- 
fully and  grasp  the  meaning  of  each  line.  In  short,  he  has  to  think. 
To  form  a  MENTAL  PICTURE  of  the  piece  illustrated  is  more  difficult 
than  mere  copying;  it  is  also  more  beneficial. 


That  faculty  of  imagining,  that  mental  picturing  so  necessary  10 
the  good  draftsman  or  designer,  can  be  developed  within  every  stu- 
dent. It  is  a  part  of  his  development,  just  as  an  understanding  of  the 
meaning  (either  definite  or  conventional)  of  each  line  of  a  drawing 
is  a  part  of  his  development. 

Convinced  of  this  fact,  the  author  has  arranged  these  lessons  in  a 
manner  which  he  believes  will  attract  and  hold  the  attention  of  the 
student.  Each  lesson  will  guide  the  student  by  easy  steps,  illustrate 
some  fundamental  point  in  Mechanical  Drawing,  and  work  as  a  whole 
towards  the  development  of  the  creative  draftsman. 

The  results  obtained  by  the  author  at  the  Carnegie  Technical 
Schools,  through  this  mode  of  teaching,  justify  him  in  this  belief,  and 
prompt  him  to  place  within  reach  of  every  one  interested  in  the  sub- 
ject this  simple  treatise,  which  he  hopes  will  be  as  fruitful  in  the  hands 
of  others  as  it  has  been  in  his. 

CHARLES  C.  LEEDS. 
March  15,  1908. 


192820 


UNIVERSITY 


OF 


LESSON  No.  i. 


PENCILS.— It  is  very  important  that  the  student  of  Mechanical 
Drawing  should  have  good  tools  to  work  with,  and  just  as  important 
that  he  should  learn  to  take  good  care  of  them  that  they  may  be  always 
ready  for  use.  No  tool  is  more  used  in  mechanical  drawing  than  a 
lead  pencil,  yet  no  tool  is  so  greatly  abused,  mainly  because  it  is  not 
very  expensive. 

Pencils  for  drawing  are  made  of  various  degrees  of  hardness  to  suit 
the  purposes  for  which  they  are  to  be  used.  There  are  a  number  of 
methods  of  designating  the  degree  of  hardness, — one  of  the  commonest 
being  to  mark  them  2H,  4.H,  6H,  etc.,  the  harder  the  pencil,  the  higher 
the  number  preceding  the  H. 

For  drawing  on  the  common  Manilla  papers,  4!!  is  a  very  satis- 
factory pencil,  though  6H  wears  better  and  does  not  require  to  be 
sharpened  so  often. 

To  do  accurate  drawing,  it  is  necessary  to  keep  the  pencil  well 
sharpened.  The  following  methods  for  sharpening  are  highly  desirable. 

ROUND  POINT.— The  first  method  is  known  as  the  "Round 
Point."  This  is  produced  by  first  cutting  away  the  wood,  as  shown  in 
the  illustration,  Fig.  i,  and  then  sharpening  the  lead  on  a  file. 

Round  not  straight. 


Do  this  with  your  knife. 


File  the  point. 


FIG. 


About  one  inch  from  the  end  of  the  pencil,  beginning  on  one  of  the 
six  corners,  cut  away  the  wood  in  a  clean  manner  so  as  to  bare  about 
f "  of  the  lead ;  then  sharpen  it  on  the  file  by  drawing  it  towards  you. 
Turn  the  pencil  slowly  away  from  you,  taking  a  fresh  hold  with  each 
stroke,  so  as  to  keep  the  pencil  turning  on  its  axis  as  it  is  moved  along 
the  file. 


I 


FIG.  2. 


FLAT  POINT.— The  "Flat  Point"  is  very  useful  when  it  is 
desired  to  draw  very  fine  accurate  lines,  such  as  the  center  lines,  con- 
struction lines,  etc.  In  sharp- 
ening the  flat  point,  enter  the 
knife  about  one  inch  from  the 
end  of  the  pencil  on  one  of  the 
flat  sides  (not  corner),  and  cut 
away  the  wood  in  the  manner 
shown  in  the  illustration,  Fig.  2, 
baring  about  one-half  inch  of 
the  lead. 

To  sharpen  the  lead,  slide  it 
back  and  forth  along  the  file,  forming  a  long  chisel-like  point. 

The  flat  side  of  the  lead  should  parallel  the  flat  side  of  the  pencil 
when  the  point  is  finished. 

PAPER. — The  drawing  paper  commonly  used  in  commercial  draft- 
ing rooms  is  known  as  Manilla  paper. 

There  are  a  great  many  different  grades  of  this  paper  manufactured, 
but  the  main  points  necessary  to  keep  in  mind  when  making  a  selection 
are:  color,  erasing  qualities,  and  toughness  of  fibre. 
The   standard    sizes   of   drawings 

adopted   by   the    Carnegie   Technical         f  i  4 

Schools  are:    A  sheets   22"X3o",   B 
sheets  I5"X22",  and  C  sheets  n"X 


Drawing  paper  should  be  fastened 
to  the  board  as  smoothly  as  possible; 
for  it  is  very  difficult  to  make  an  accu- 
rate drawing  on  paper  which  does  not 
lie  flat  on  the  board. 


FIG.  3. 


LESSON   No.  i.— Continued. 


The  method  of  mounting  paper,  shown  in  the  above  illustration, 
Fig.  3,  needs  very  little  explanation,  and  if  the  student  follows  the  direc- 
tions with  reasonable  care,  the  result  will  be  entirely  satisfactory. 
Place  the  tacks  in  the  order  numbered,  stretching  the  paper  in  the 
direction  indicated  by  the  arrows. 

Push  the  tacks  well  down,  so  that  the  heads  bind  the  paper  closely; 
this  will  also  enable  the  T  square  to  slip  over  them  easily  without 
knocking  small  chips  out  of  the  edge  of  the  blade. 

DRAWING  BOARD. —T  SQUARE.  —  TRIANGLES.  —  The 
Drawing  Board  should  be  made  of  a  soft  wood,  well-seasoned  white 


B 


12. 


FIG. 


pine  preferred,  so  that  the  thumb  tacks  may  be  easily  pushed  into  or 
drawn  from  it. 

One  end  of  the  board  must  be  perfectly  straight,  as  well  as  smooth, 
and  free  from  bumps  or  high  spots. 

A  T  Square  of  well-seasoned  pear  wood  is  inexpensive  and  should 
give  satisfactory  results. 

The  inside  edge  of  the  head  and  the  upper  edge  of  the  blade  should 
be  perfectly  straight,  and  be  smoothly  and  accurately  finished. 


The  Triangles  commonly  used  by  draftsmen  are  the  45°  and  the 
3o°-6o°  angles ;  and  it  is  preferable  that  they  should  be  made  of  some 
transparent  material. 

The  student  should  realize  the  necessity  of  learning  to  use  these 
tools  properly  if  he  desires  to  do  accurate  work.  The  head  of  the  T 
Square  should  be  kept  pressed  against  the  edge  of  the  board  when  in 
use;  place  the  hand  at  A,  Fig.  4,  rather  than  at  B,  and  press  the  blade 
flat  against  the  board  by  placing  the  thumb  at  C. 

The  student  should  work  from  the  left  side  of  the  board  at  all  times, 
and  when  drawing  -vertical  lines,  he  should  use  the  left  side  of  the 
triangle  as  a  ruling  edge. 

The  left  side  of  the  triangle  is  the  most  natural  one  to  use,  as  the 


FIG.  5. 


arm  is  held  in  an  easy  position  when  drawing  a  line  away  from  the 
square  blade.  Besides,  when  tracing  with  ink,  the  student  would  find 
it  extremely  awkward  and  tiresome  to  use  the  right  side  of  the  triangle. 


LESSON    No.  i.— Continued. 


Hence  this  general  statement:  Accurate  work  is  practically  impos- 
sible when  both  sides  of  the  triangle  are  used  to  rule  vertical  lines  on 
the  same  drawing.  The  reason  is  that  triangles  are  very  often  inaccu- 
rate. 

Fig.  4  shows  where  the  trouble  lies  and  gives  the  student  a  way  of 
testing  the  accuracy  of  his  own  triangles. 

RULING  LINES. — A  very  common  cause  of  inaccurate  work  is 
the  careless  manner  in  which  the  lines  of  a  drawing  are  ruled;  if  the 
student  will  consider  the  angle  formed  by  the  edge  of  the  T  Square 
and  the  surface  of  the  paper  as  a  groove,  and  then,  leaning  the  pencil 
slightly  away  from  the  ruling  edge,  drag  the  point  along  this  groove, 
he  will  have  no  difficulty  in  ruling  a  straight  line. 

(a)  in  the  illustration,  Fig.  5,  shows  the  correct  method,  and  (b)  the 
incorrect  one. 

WEARING  THE  PENCIL  POINT.— Draftsmen  pick  up  a 
good  many  little  tricks  or  habits  that  are  of  advantage  in  their  work. 
One  of  them  is  a  method  of  wearing  the  pencil  point  in  such  a  way 
that  it  will  stay  sharp  a  long  time. 

The  Flat  Point  is  shown  in  illustration  (a),  Fig.  6,  and  the  method 
is  too  evident  to  need  further  explanation. 


A 


as  shown  at  (b),  preserve  for  a  long  time  the  sharp  conical  point  of  the 
pencil. 

SCALE. — The  draftsman's  flat  rule  (or  scale,  as  it  is  generally 
termed),  which  is  graduated  in  sixteenths  on  one  edge  and  thirty- 
seconds  on  the  other,  will  be  found  very  satisfactory. 

When  selecting  a  scale  it  is  advisable  to  choose  one  with  the  grad- 
uations cut  in  a  white  surface,  as  the  strain  on  the  student's  eyes  is 
much  less  than  when  using  a  steel  scale  or  one  of  plain  boxwood. 

ACCURACY. — If  we  stop  to  analyze  the  mechanical  part  of  the 
work  of  a  draftsman,  we  realize  that  a  great  portion  of  his  work  con- 
sists in  placing  points  on  the  surface  of  the  paper  and  connecting  them 
with  lines,  or  in  drawing  lines  through  them. 

When  enough  of  these  points  and  lines  have  been  placed  upon  the 
paper,  the  drawing  of  the  figure  is  complete. 

To  make  a  mechanical  drawing  accurately,  it  is  absolutely  essential 
that  the  points  be  placed  in  their  proper  positions. 

In  connecting  them  with  lines,  or  in  drawing  lines  through  them, 
the  lines  should  pass  through  the  center  of  the  points. 

If  the  student  is  unable  to  do  this  properly,  it  naturally  follows  that 
he  is  unable  to  make  an  accurate  drawing. 

LINE  THROUGH  A  POINT.— ist.  With  the  round-point  end 
of  the  pencil,  make  twenty  small  points  upon  the  paper,  one  above 

/— Point 


FIG.  6. 


When  ruling  a  line  with  the  round  point,  turn  the  pencil  slowly  and 
deliberately,  so  that  it  revolves  on  its  axis  as  it  is  dragged  along  the 
ruling  edge. 

This  method  will  result  in  lines  of  an  even  thickness  and  color,  and, 


FIG.  7. 

another,  and  about  J  of  an  inch  apart;  then,  with  the  flat -point  end  of 
the  pencil,  rule  with  the  T  square  a  fine,  clear,  straight,  horizontal  line 
through  each  point,  as  shown  in  Fig.  7. 

These  lines  may  be  6  or  8  inches  long.     Rule  ten  of  them  by  adjust- 
ing the  blade  of  the  T  square  up  to  the  point,  and  ten  by  placing  the 


LESSON    No.   i.— Continued. 


FIG.  8 


THE 

UNIVERSITY 

OF 


LESSON    No.  i.— Continued. 


pencil  point  in  position  and  bringing  the  ruling  edge  gently  up  to  it. 
These  fine  lines  are  called  "construction  lines,"  from  the  fact  that 
•when  used  in  practice,  the  drawing  is  built  upon  them.  The  student 
should  endeavor  to  "split"  the  point  each  time. 

Now,  with  the  round-point  end  of  the  pencil,  "line  in"  about  3 
inches  of  each  line  to  the  right  of  the  point. 

By  the  term  "line  in,"  we  mean  to  make  that  portion  of  the  line 
heavier,  so  that  the  result  will  be  a  strong,  clear  line,  such  as  should  be 
shown  on  a  finished  drawing.  When  lining  in,  the  student  should  be 
very  careful  to  cover  the  construction  line  perfectly. 

Lining  in  a  little  above  or  a  little  below  the  construction  line  results 
in  inaccurate  work. 

2d.  Repeat  above,  ruling  vertical  lines  and  45°  lines,  using  the  T 
square  and  the  45°  triangle. 

LAYING  OFF  DIMENSIONS.— 3d.  Draw  fifteen  straight  lines 
just  4  inches  long;  these  lines  to  be  horizontal,  vertical,  and  45°. 

In  each  case  use  the  method  described  above;  first  a  fine  construc- 
tion line  more  than  4  inches  long,  then,  using  the  scale  in  the  manner 
shown  in  the  illustration,  Fig.  8,  lay  off  two  points  which  are  exactly 
4  inches  apart,  and  "line  in"  that  part  of  the  construction  line  between 
points. 

THREE-INCH  SQUARE.— 4th.  Using  the  T  square  and  the  45° 
triangle,  construct  a  3-inch  square.  Rule  the  lines  in  the  order  shown 
by  numbers  in  the  illustration,  Fig.  9. 


Lines  i,  2,  and  3  should  be  construction  lines  at  first. 
Finish  the  square  by  lining  in  these  sides. 


FIG.  9. 

When  the  square  is  finished,  the  length  of  each  side  should  be 
exactly  3  inches. 


LESSON  No.  2. 


ACCURACY.— The  student  should  at  all  times  endeavor  to  make 
accurate  drawings,  and  he  will  find  that  it  is  only  by  constant  effort  on 
his  part  that  this  can  be  accomplished. 

This  lesson  is  a  test  in  accuracy,  and  it  is  necessary  that  the  student 
should  exercise  great  care  in  laying  out  these  figures. 

COMPASS  POINTS.— Get  the  pencil  compasses  ready  for  use. 

In  preparing  the  large  compass,  remove  the  pencil  leg  and,  with 
the  file,  produce  a  "flat  point"  very  similar  to  the  "flat  point"  of  the 
pencil.  Trim  off  the  sides  so  as  to  get  a  narrow  "  flat  point "  as  shown 
in  the  illustration,  Fig.  10. 


The  flat  side  of  the  lead  should  be  set  at  right  angles  with  the 
needle  point.     If  this  requirement  is  not  met  with,  the  compass  tends 


Fio.  10. 

The  pencil  point  of  the  spring-bow  compass  should  be  sharpened 
in  the  same  manner,  except  that  the  finished  point  should  be  slightly 
narrower  than  the  one  in  the  large  compass. 

SETTING  LEAD.— When  adjusting  the  legs  of  the  large  com- 
pass, see  that  the  pencil  point  is  slightly  shorter  than  the  needle  point ; 
about  to  the  shoulder  of  the  latter. 


Fio.  ii. 

to  open  when  it  is  turned  in  one  direction,  and  to  close  when  turned  in 
the  other. 


LESSON    No.  2.— Continued. 


After  the  compass  legs  are  properly  adjusted  for  length,  test  the 
setting  of  the  lead  by  drawing  a  circle  clockwise,  then,  without  remov- 
ing the  needle  point  from  the  paper,  swing  one  counter-clockwise. 
The  result  should  be  one  clear  sharp  circle;  if  this  is  not  the  case,  the 
lead  should  be  adjusted  to  correct  the  error. 

SETTING  COMPASS.— With  the  large  compass,  take  a  radius 
of  ij  inches  and  describe  a  3-inch  circle. 

Now,  test  the  circle  for  a  diameter  of  3  inches,  using  the  scale. 
Reset  the  compass  and  repeat  above  test  several  times,  so  as  to  gain 
confidence  in  setting  the  compass.  When  setting  the  latter,  handle  it, 
and  also  the  scale,  as  shown  in  the  illustration,  Fig.  n. 


FIG.  is. 

TANGENT  CIRCLES.  — TRIANGLE. —  Describe  three  2-inch 
circles  tangent  to  one  another. 

Surround  the  circles  by  a  tangent  triangle.  "Line  in"  the  triangle 
and  test  it  for  accuracy,  using  the  dividers;  the  sides  should  be  of 
equal  length. 


Repeat  this  three  times. 

Great  care  should  be  exercised  by  the  student  in  laying  out  this 
figure,  which  presents  so  many  chances  for  error  that  it  is  quite  diffi- 
cult to  draw  correctly. 

SQUARE. — Construct  a  3-inch  square,  using  the  T  square  and 
triangle.  The  square  to  have  rounded  corners  of  £-inch  radius,  made 
with  the  bow-pencil  compass. 

The  finished  square  should  be  "lined  in"  so  that  there  are  no 
visible  joints. 

Where  rounded  corners  join  straight  lines  on  a  mechanical  draw- 
ing, the  joint  should  be  so  nearly  perfect  as  to  be  unnoticeable.  Care 
in  these  little  details  adds  greatly  to  the  attractiveness  of  a  drawing, 
and  they  should  never  be  overlooked. 


/  2  3 

FIG.  13. 

The  student  should  observe  that  in  the  illustration,  Fig.  13,  the 
square  is  first  laid  out  in  faint  construction  lines,  then  the  corners  are 
rounded,  and,  finally,  the  sides  are  "  lined  in." 

The  rounded  corner  lines  should  be  made  as  heavy  as  it  is  desired 
to  make  the  rest  of  the  outline,  so  that  in  "lining  in"  the  sides,  the 
lines  may  be  made  of  the  same  weight. 


LESSON    No.  3. 


FLANGED  PIN. — Make  a  full-size  three-view  outline  drawing  of 
the  flanged  pin  shown  in  the  illustration,  Drawing  C-iooo. 

View  (a)  shows  the  shank  end  of  the  pin  as  seen  from  the  position 
of  (a).  View  (A)  is  a  side  view  of  the  flanged  pin,  and  (c)  is  a  view 
of  the  round  end  as  seen  from  the  position  of  view  (c).  The  student 
should  study  the  illustration  carefully,  and  try  to  understand  clearly 
the  meaning  of  each  line.  The  position  of  each  view  is  given  in  rela- 
tion to  the  edge  of  the  sheet. 

THE  DRAWING.— To  make  the  drawing,  first  lay  out  the  center 
lines,  as  they  fix  the  positions  of  the  views.  Second,  draw  view  (a), 
throwing  in  the  circles,  then,  with  the  T  square  and  45°  triangle,  construct 
the  square  representing  the  shank  end.  Third,  draw  view  (b),  setting 
the  compasses  with  care  each  time,  so  that  the  circles  are  drawn  exactly 


to  scale.  Fourth,  lay  off  the  lengthwise  dimensions  of  the  pin,  then 
draw  vertical  construction  lines  through  these  points  (lines  of  any 
length) ;  now  place  the  T  square  so  as  to  project  the  horizontal  lines  of 
the  pin  from  the  end  views.  With  a  J-inch  radius,  throw  in  the  curved 
lines  representing  the  chamfer  on  the  shank  end.  Observe  how  the 
radius  center  line  is  projected  from  the  end  vit-\v. 

FINISHED  DRAWING.— In  finishing  the  drawing,  "line  in" 
the  whole  outline  with  care  to  give  it  a  neat  appearance,  and  to  make 
it  clear  and  distinct,  so  that  all  the  lines  can  be  easily  seen  through  the 
tracing  cloth.  Do  not  put  in  any  of  the  dimensions.  The  finished 
drawing  should  show  only  the  outlines  of  the  pin  with  the  vertical  and 
horizontal  center  lines. 


Cenffr  Lines 


CLASS  Industrial          TRADE  Machinist 
NAME  John  W.  Roberts       DATE  Feb.  /6_  06. 


THE   CARNEGIE   TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL   DRAWING 


FLANGED  PIN 


SCALE  full  Size 


owa.  wo.  C./OOO 


-        OF   THE 

UNIVERSITY 


LESSON    No.  4. 


MACHINE  BOLT.— Make  a  full-size  three-view  mechanical 
drawing  of  the  ij-inch  machine  bolt  shown  in  the  illustration,  Drawing 
C-iooi.  View  (a)  represents  the  end  of  the  bolt  head  as  seen  from 
the  position  of  (a).  View  (b)  is  a  side  view  of  the  bolt  and  hexagon 
nut.  View  (f)  is  an  end  view  of  the  threaded  end  of  the  bolt  and  of 
the  hexagon  nut  as  seen  from  the  position  of  (c).  The  positions  of 
the  views  are  given  in  relation  to  the  edges  of  the  paper. 

THE  DRAWING.— Lay  off  the  center  lines  first,  so  that  the 
positions  of  the  views  are  fixed  at  the  beginning;  do  not  let  them 
"happen"  as  regards  location. 

In  drawing  view  (a),  lay  out  the  aj-inch  construction  circle,  and 
then  with  the  T  square  and  45°  triangle,  draw  in  the  outline  of  the  head. 

View  (c)  is  drawn  in  the  same  manner,  that  is,  first  the  zf-inch 
construction  circle,  then,  using  the  T  square  and  the  3o°-6o°  triangle 
draw  the  outline  of  the  hexagon  nut,  and  finally  throw  in  the  ij-inch 
circle  to  represent  the  end  of  the  bolt. 

Having  drawn  views  (a)  and  (f),  now  lay  off  the  lengthwise  dimen- 
sions of  view  (b),  and  draw  vertical  construction  lines  through  these 
points  (lines  any  length).  With  the  T  square,  project  the  horizontal  lines 
of  the  bolt  from  the  end  views,  these  lines  to  be  light  construction  lines, 
until  their  true  length  is  known.  Now  swing  in  the  various  radii, 
make  them  as  heavy  as  the  final  outline  is  to  be,  and  line  in  the  bolt 


and  nut  completely,  so  that  the  whole  outline  stands  out  clearly  and 
distinctly. 

SCREW  THREADS.— The  threaded  end  of  the  bolt  is  indicated 
by  alternate  light  and  heavy  lines,  the  heavy  lines  being  shorter  than 
the  light  ones.  This  is  a  conventional  method  of  indicating  screw 
threads,  and  it  has  the  merit  of  being  easily  understood  and  is  inex- 
pensive. 

While  it  is  not  essential  that  the  space  between  the  light  lines  should 
be  just  the  same  as  the  pitch  of  the  thread,  or  that  the  lines  should  be 
sloped  at  exactly  the  correct  angle,  it  is  of  considerable  importance 
that  the  threaded  surface  as  a  whole  should  look  approximately 
correct. 

When  the  slope  is  correct  for  a  single-thread  screw,  a  line  drawn  at 
right  angles  to  the  center  line  of  the  screw  should  touch  the  end  of  one 
of  the  thread  lines  at  one  side  and  pass  midway  between  that  line  and 
the  next  at  the  opposite  side,  as  indicated  by  the  light  dash  line  d-e. 
In  other  words,  the  slope  equals  half  of  the  pitch  of  the  thread. 

Place  the  dimensions  just  as  shown  in  the  illustration,  and  make 
the  figures  carefully,  so  that  there  can  be  no  doubt  as  to  their  meaning. 
The  dimensions  which  refer  to  the  position  of  the  different  views 
should  be  left  off,  as  they  were  intended  to  aid  the  student  in  locating 
the  views,  and  have  no  other  value. 


CLASS  Industrial        TRADE  Machinist 

N AMI:  John  W.  Roberts   DATE  Feb.  20.  06. 


THE   CARNEGIE   TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL,     DRAWING 


MACHINE  BOLT 


.SCALE.  Full  Size 


ona.No.C.IOOl 


OF  THE 

UNIVERSITY 

OF 


LESSON    No.  5. 


LETTERING.— The  average  student  does  not  fully  appreciate 
the  value  of  being  able  to  letter  well,  and  while  he  is  seldom 
pleased  with  his  lettering,  he  usually  does  not  like  to  devote 
the  necessary  time  to  practice.  A  great  many  young  draftsmen 
reach  the  point  where  they  are  able  to  make  a  neat,  workmanlike 
drawing,  the  appearance  of  which  they  will  spoil  when  they  letter. 
and  dimension  it. 

In  making  a  study  of  the  types  of  letters  illustrated,  take  especial 
notice  of  the  oval,  which  is  the  basis  of  most  of  the  lower-case  letters, 
and  observe  the  proportions  of  this  type;  note  also  the  slope  of  both 
types. 

The  capitals  are  used  mainly  for  titles  and  headings,  while  the 
lower-case  letters  are  used  for  all  notes  shown  on  drawings  and  for  all 
other  purposes,  except  for  titles  and  headings. 

As  an  aid  in  learning  to  letter,  it  is  well  to  use  guide  lines  as  shown 


in  the  illustration.  The  student  will  find  the  slope  guide  lines  a  great 
help  also  in  making  letters  of  uniform  appearance. 

FIGURES. — What  has  been  written  in  regard  to  lettering  applies 
equally  well  to  figures. 

It  is  of  great  importance  that  the  student  should  learn  to  make  his 
figures  so  well  that  no  one  should  have  any  trouble  in  reading  them 
easily  and  quickly.  Mistakes  in  the  shops  are  very  frequently  caused 
by  poorly  written  figures  on  drawings,  and  these  mistakes  are  often 
very  costly.  The  value  of  using  great  care  at  all  times  in  placing  the 
dimensions  on  drawings  is  thus  clearly  shown. 

THE  LESSON. — Make  a  neat  pencil  copy  of  the  illustration, 
using  care  with  both  letters  and  figures;  note  carefully  the  proportions 
of  both.  Leave  off  figures  showing  spacing  of  guide  lines,  as  these 
were  intended  merely  as  an  aid  to  the  student  in  laying  out  his  lesson 
sheet. 


•3ffiaHHnH^.ZJlZr. 


JLt^Jriy,'         < 


......... 

•f«»  /  /   JJ  I  /     // 

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'nthcMf^hjRlri}H(  itihii.^i h^M^Mi 
tii-H-ffi-H  //////  y  /'//////  /77  //// 


, 

J  IT      I 


CLASS    Industrial    TRADE     Machinist 
NAME    John  W.  Roberts  ct.rz    Nov.  12,  06 


THE  CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 
SCHOOL  OF  APPRZNTICCS  AND  JOURNEYMEN 

MECHANICAL    DP  AWING 


LETTERING  -  F/GURES 

SCALE    Full  Size  •  owa.No.  C-/002 


Of   THE 

UNIVERSITY 

OF 


LESSON    No.  6. 


SKETCHING. — Whatever  course  in  mechanical  drawing  the  stu- 
dent may  pursue,  he  will  sooner  or  later  desire  to  know  something  about 
sketching,  or,  at  least,  he  will  feel  the  need  of  it. 

A  knowledge  of  sketching  is  exceedingly  useful  to  men  of  most  of 
the  trades,  and  the  lessons  on  this  subject  have  been  planned  with  the 
belief  that  they  may  assist  the  students  to  use  their  pencils  more  freely 
and  easily  in  making  simple  mechanical  drawings  free-hand. 

METHOD.— The  method  that  we  shall  follow,  we  shall  call  the 
"Short -stroke  Method,"  from  the  fact  that  as  we  draw  a  line  in  any 
direction,  it  is  not  made  by  a  single  stroke  of  the  pencil,  but  by  a  series 
of  short  strokes.  There  should  be  the  smallest  possible  opening  be- 
tween the  ends  of  these  short  lines,  and  it  would  be  better  still  if  the 
ends  were  to  just  touch  without  overlapping. 

The  object  of  using  these  short  strokes  is  to  enable  the  student  to 
correct  an  error  in  direction  at  any  point  along  the  line.  The  result  is 
that  the  general  direction  of  the  line  is  straight,  and  though  there  may 
be  slight  errors  along  the  line,  they  in  nowise  cause  any  doubt  as  to 
its  meaning. 

PENCILS. — For  sketching,  a  pencil  equalling  an  H  or  HB  in  hard- 
ness will  give  very  satisfactory  results,  though  a  zH  Koh-i-noor  will 
last  much  better.  The  latter,  however,  is  just  a  little  too  hard  except 
when  used  on  Manilla  paper. 

Learn  to  hold  the  pencil  easily  and  naturally  between  the  first  and 
second  fingers  and  the  thumb,  in  a  manner  very  similar  to  that  used  in 
writing. 


Do  not  turn  the  paper  to  suit  the  direction  in  which  a  line  is  to  be 
drawn,  but  fasten  it  down  to  the  drawing  board  and  try  to  develop  that 
freedom  of  movement  of  fingers,  wrist,  and  arm  which  will  enable  one 
to  draw  a  line  in  any  direction  with  equal  ease. 

In  drawing  straight  lines  as  indicated  on  the  illustration,  the  student 
will  soon  discover  that  they  are  made  in  certain  directions  by  a  move- 
ment of  the  wrist  mainly.  In  other  directions  it  is  mostly  a  movement 
of  the  fingers  which  gives  the  best  results. 

It  is  quite  difficult  to  make  neat  circles  free-hand,  but  by  putting 
into  practice  the  following  suggestions,  the  student  should  obtain  satis- 
factory results. 

The  student  should  sit  upright  while  drawing,  so  that  he  may  the 
better  get  a  clear  view  of  his  work  as  a  whole.  By  having  the  head 
well  up  over  the  work,  the  eyes  can  direct  the  movements  of  the  pencil 
better,  and  they  are  in  a  better  position  to  see  if  the  desired  shape  is 
growing  under  the  pencil,  than  if  held  close  to  the  work.  Start  at  a 
point  on  the  left  side,  as  indicated  by  the  arrows,  and  with  short  strokes 
form  the  upper  half  of  the  circle.  Then,  starting  at  the  same  point, 
form  the  lower  half  in  the  same  manner. 

THE  LESSON.— Fasten  the  drawing  paper  smoothly  to  the 
board  and  divide  it  into  sections,  as  shown  in  the  illustration. 

The  straight  lines  should  be  drawn  about  J  inch  apart  and  in  the 
directions  indicated  by  the  arrows. 

Draw  the  circles  to  the  sizes  shown,  without  using  a  rule;  try  to 
see  how  nearly  correct  you  can  make  them  by  the  eye. 


CLASS  Industrial         TRADE  Machinist 

HAME  John  W.  Roberts        DATC  Mar.  PO-  Of. 


THE:  CARNEGIE  TECHNICAL 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOUR 

MECHANICAL    CrffAWtHG 


SCHOOLS 


SKETCHING 


SCALE  Full  Size  owe.  NO.  C.  IO03 


OF    THE 

UNIVERSITY 

OF 


LESSON    No.  7. 


PROPORTIONS. — It  is  a  very  valuable  acquirement,  when 
sketching,  to  be  able  to  make  the  details  of  a  drawing  of  the  proper 
proportions  in  relation  to  each  other. 

The  scale  of  a  sketch  is  of  little  importance,  provided  it  is  large 
enough  to  show  clearly  the  piece  or  pieces  we  desire  to  illustrate.  But 
that  which  is  of  importance  is  that  each  piece,  or  detail  of  the  piece, 
should  be  drawn  to  the  same  scale. 

To  obtain  this  result  it  is  quite  necessary  that  the  student  should 
train  his  faculty  of  observation  so  as  to  have  a  sense  of  measurement, 


and  so  that,  without  the  aid  of  a  rule,  he  may  be  able  to  draw  a  sketch 
approximately  to  a  given  size. 

The  student  will  be  helped  to  develop  this  faculty  if,  in  sketching, 
he  practises  drawing  to  a  certain  scale  or  to  given  dimensions. 

LESSON. — Make  a  neat  free-hand  full-size  drawing  of  the  figures 
shown  in  the  illustration.  Draw  each  figure  to  the  dimensions  given, 
as  nearly  as  possible,  without  using  a  rule. 

Observe  that  two  views  are  shown  of  each  piece,  and  try  to  see 
the  relation  between  the  views. 


i    r 


<\j 


4 


THE   CARNEGIE  TECHNICAL  SCHOOLS 


Ci/iss  Industrial          T/?ADE  Machinist 

John  W.Roberts     DATE  Mar.  PO.O6. 


PITTSBURGH,  PA. 
SCHOOL  Of  APPREMTICZS  AND  Jo 

MECHANICAL    DRAWING 


SKETCHING 

Size  Dw6.no.  CLIO04 


LESSON    No.  8. 


METHOD  OF  HOLDING  PEN.— In  learning  to  trace,  one  of 
the  first  problems  which  confronts  the  student  is  how  to  hold  the 
instruments. 

In  general,  the  ruling  pen  and  the  pen  point  of  the  compass  should 
be  held  in  such  a  manner  as  to  bring  the  points  of  both  jaws  on  the 
paper  at  the  same  time,  as  shown  at  (b)  of  the  illustration,  Fig.  14. 


tt 


a 


Fir..    14. 


Do  not  lean  the  jien  either  toward  the  ruling  edge  or  away  from  it,  but 
hold  it  in  a  vertical  plane,  thus  obtaining  clean  even  lines  free  from  a 
ragged  edge. 

While  the  pen  should  not  be  leaned  toward  or  away  from  the  ruling 
edge,  it  will  be  found  that  the  ink  will  flow  more  freely  if  the  pen  is 
leaned  slightly  in  the  direction  in  which  the  line  is  being  ruled,  as  shown 
at  (a). 


When  using  the  pen  compass  for  large  circles,  the  legs  may  be  bent 
at  the  joints,  so  as  to  meet  these  conditions. 

TRACING  CLOTH.— The  student  will  find  one  side  of  the  trac- 
ing cloth  with  a  glazed  or  calendered  surface,  while  the  other  side  has 
a  dull  finish.  If  the  glossy  side  is  used,  it  will  be  necessary  to  dust  the 
surface  with  powdered  chalk  or  talcum  powder,  as  the  ink  will  not  flow 
freely  otherwise.  In  a  great  many  drafting  rooms  the  dull  side  of  the 
cloth  is  used  from  preference,  as  it  takes  ink  very  well  without  powder 
of  any  kind,  though  the  powder  makes  the  ink  flow  more  freely. 


©I 


1st.  Circles  and  Radii 


3rd.  Vertical  lines 


2nd  Horizontal  lines 


4th.  Angular  lines 


Fin.   15. 


CARE  OF  PENS. — A  common  mistake  of  most  beginners  is  to 
fill  the  pen  with  too  much  ink,  with  the  result  that,  before  they  realize 
it,  there  is  a  big  blot  on  their  work.  This  is  not  necessarily  caused  by 
the  pen  being  filled  too  full,  but  it  is  frequently  the  cause.  It  is  better 
to  fill  the  pen  oftener  and  to  use  less  ink  at  one  time. 

Another  very  good  habit  to  acquire  is  to  wipe  out  the  pen  each 


Of  THE 

UNIVERSITY 


LESSON    No.  8.— Continued. 


time  fresh  ink  is  to  be  put  in,  as  the  ink  flows  more  freely  from  a  clean 
pen  than  from  a  dirty  one. 

TRACING  FLANGED  PIN.— Make  a  tracing  of  the  pencil 
drawing  of  the  flanged  pin. 

When  beginning  a  tracing,  tack  the  cloth  down  carefully  over  the 
pencil  drawing,  then  set  the  compass  pen  to  the  desired  width  of  line 
bv  testing  on  the  edge  of  the  sheet,  and,  after  it  is  properly  adjusted, 


throw  in  all  the  circles  and  radii.  Then,  beginning  at  the  top,  rule  in 
the  horizontal  outlines;  next,  beginning  at  the  left  side,  rule  in  the 
vertical  outlines  and  finally  the  angular  lines. 

In  ruling  horizontal  lines,  use  the  T  square  as  a  ruling  edge.  For 
vertical  lines,  use  the  left  side  of  the  triangle,  which  should  be  held 
against  the  T-square  blade. 

Do  not  use  the  scale  as  a  ruling  edge. 


OF  THE 

UNIVERSITY 

OF 


LESSON    No.  9. 


TRACING  MACHINE  BOLT.— As  mentioned  in  Lesson  No.  8, 
begin  by  adjusting  the  compass  pen  to  the  width  of  line  desired  for  an 
outline.'  In  deciding  on  the  width  of  line,  the  student  should  bear  in 


01: 


1st.  Circles  and  Radii 


3rd.  Vertical  lines 


o 


2nd  Horizontal  lines 

Dimension  lines 


.  Angular  lines 

Projection   lines 


Sfh.  Projection  and  Dimension  lines— 

Dimensions-  Notes 
FIG.  1 6. 

mind  that  to  get  blue-prints  with  clear  white  lines,  it  is  necessary  that 
the  lines  of  the  tracing  be  fairly  heavy;  not  the  fine,  "pretty"  lines 
that  beginners  are  so  prone  to  use. 


The  illustration  shows  the  various  steps  in  making  a  tracing:  First, 
throw  in  all  the  circles  and  radii ;  then,  beginning  at  the  top,  rule  in  all 
the  horizontal  outlines;  next,  starting  at  the  left  side,  rule  in  all  the 
vertical  outlines;  and,  finally,  rule  in  the  angular  outlines. 

Now,  adjusting  the  pen  to  a  much  finer  line,  rule  in  the  projection 
lines;  these  lines  for  drawings  of  small  figures  should  be  composed  of 
dashes  i  to  f  inch  long,  and  for  large  figures  J  to  f  inch  long.  Do  not 
let  the  projection  lines  touch  the  figure,  but  leave  a  slight  opening 
between  the  end  of  the  line  and  the  figure. 

Next,  rule  in  the  dimension  lines ;  these  lines  for  drawings  of  small 
figures  should  be  solid  except  for  the  opening  left  for  the  dimension, 
but  on  drawings  of  large  figures  they  may  be  broken  lines  of  long 
dashes,— the  length  to  suit  the  size  of  the  drawing. 

Now,  place  the  arrow  heads  on  the  dimension  lines  and  put  in  the 
dimensions,  using  care  to  make  the  figures  clearly. 

FINISHED  DRAWING.— In  the  finished  drawing  there  should 
be  a  marked  contrast  between  the  weight  of  the  outlines  of  the  figure, 
and  of  the  center,  projection,  and  dimension  lines;  the  latter  should  be 
decidedly  lighter  than  the  outlines.  When  these  various  lines  are 
drawn  to  the  proper  proportions  and  are  well  arranged,  the  figure 
seems  to  stand  out  by  itself  and  is  much  more  easily  under- 
stood. 

When  the  drawing  is  completed,  print  the  title  on  neatly  and  care- 
fully, as  the  looks  of  a  good  drawing  will  be  spoiled  if  the  printing  is 
done  in  a  careless,  slipshod  manner. 

Use  a  Gillott's  No.  303  pen  point  for  lettering  and  dimensioning 

the  drawing. 


LESSON    No.   10. 


HIDDEN  SURFACES.— Until  the  present  time  we  have  been 
using  lines  which  could  be  seen  on  the  surface,  or  which  represented 
the  surface  of  the  figures  that  we  have  used  as  subjects  for  our  draw- 
ing lessons. 

In  mechanical  drawing  it  is  constantly  necessary  to  show  by  some 
means,  surfaces  or  details  of  parts  that  are  hidden  from  view  behind 
the  surface  shown  by  solid  lines. 

Unless  these  surfaces  could  be  indicated  by  some  simple  method, 
it  would  often  be  necessary  to  make  additional  drawings  or,  at  least, 
additional  views  to  show  clearly  the  shape  of  the  figure  illustrated. 

The  method  commonly  used  to  indicate  these  hidden  surfaces  is  to 
draw  them  in,  in  the  proper  position,  but  to  use  dotted  lines  for  this 
purpose.  These  dotted  lines,  or  "hidden  lines,"  as  they  are  generally 
called,  have  a  distinctly  different  appearance  from  the  solid  outlines  of 


the  rest  of  the  drawing,  and  their  meaning  should  be  readily  under- 
stood. 

THE  LESSON.— These  hidden  lines  are  the  essential  feature  in 
the  present  lesson.  As  they  are  constantly  used  in  mechanical  draw- 
ing, we  wish  to  call  the  student's  attention  to  them. 

Make  a  neat  free-hand  sketch  of  the  clamp  shown  on  Drawing 
€-1005. 

Finish  your  sketch  neatly;  copy  carefully  all  dimensions,  and  be 
sure  to  place  your  name,  the  drawing  number,  and  the  title  of  the 
piece  upon  it. 

From  your  sketch  make  a  full-size  pencil  drawing  of  the  clamp; 
finish  it  completely  with  all  dimensions,  the  title,  etc. 

Use  the  "  Short -stroke  Method"  in  making  your  sketch. 


f 

TT 

$ 


THE   CARNEGIE   TECHNICAL  SCHOOLS 


ctxss  Industrial         TRAOC  Machinist 

John  W.  Roberts       DATE   Oct.  6-O6. 


PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOUR 
MECHANICAL     DRAWING 


CLAMP 


SCALE    Full  Size  DWG.NO.  C.IOO5 


LESSON    No.   ii. 


SECTIONING. — \Vhen  making  drawings  it  is  often  necessary  to 
show  at  least  one  view  of  the  piece  or  pieces  illustrated,  with  part  cut 
away,  or  "in  section,"  as  it  is  generally  termed. 

The  advantage  of  this  method  is  that  it  helps  to  show  the  shape  of 
the  piece  more  clearly,  and  often  the  dimensions  can  be  placed  to  bet- 
ter advantage  on  a  sectional  view. 

As  an  aid  in  indicating  that  a  piece  is  in  section,  the  surface  is  cov- 
ered with  lines  called  "section  lines."  These  lines  are  drawn  with  the 
aid  of  a  45°  triangle  as  a  ruling  edge,  the  triangle  being  held  against 
the  T-square  blade  and  moved  for  each  line. 

In  this  course  of  lessons  we  will  use  the  section  lines  shown  on 
Drawing  C-ioo6  for  all  metals,  the  only  variation  being  that  the  lines 


should  be  spaced  close  together  for  small  pieces  and  farther  apart  for 
large  ones. 

Where  two  or  more  pieces  assembled  together  are  shown  in  section, 
the  different  parts  are  shown  more  clearly  by  sloping  the  section  lines 
in  opposite  directions  where  the  parts  join. 

THE  LESSON.— The  important  point  in  this  lesson  is  the  method 
of  showing  a  piece  in  section. 

Make  a  neat  free-hand  sketch  of  the  sleeve  shown  on  Drawing 
C-ioo6;  copy  carefully  all  dimensions,  and  all  necessary  data. 

From  your  sketch  make  a  full-size  pencil  drawing  of  the  sleeve. 
Try  hard  for  accuracy. 


-C\| 


,1- 


f 


CLASS  Industrial          TBADC  Machinist 
NAME  John  W.Roberts  DATE  Oct.  24- O6. 


THE   CARNEGIE   TECHNICAL  SCHOOLS 


PITTSBURGH,  PA. 

SCHOOL    OF   APPPENrtCES    AND   iJo 
MECHANJCAL    DRAWING 


SCALE  Full  Size 


OWO.NO.  C.I006 


LESSON    No.   12. 


PROJECTION. — Mechanical  drawings  to  be  clearly  understood 
and  easily  read  should  be  made  after  certain  fixed  rules  as  to  the 
arrangement  of  views  in  relation  to  each  other. 

There  are  usually  several  correct  arrangements  for  the  different 
views  of  a  body,  but  in  each  of  them  the  same  relationship  between  the 


Projection   lines 


Plane 


FIG.  17. 


views  is  maintained.  To  fully  grasp  the  meaning  of  this,  a  knowledge 
of  projection  is  necessary. 

Even-  student  of  Mechanical  Drawing  should  make  a  study  of  the 
subject  of  projection,  as  a  thorough  knowledge  of  this  subject  is  neces- 
sary in  order  to  read  drawings  intelligently,  and  it  is  absolutely  essen- 
tial for  one  who  wishes  to  become  a  good  draftsman. 

The  definition  of  the  word  projection  (as  applied  to  Mechanical 
Drawing),  given  in  the  Universal  Dictionary  of  Mechanical  Drawing 


by  Prof.  Geo.  H.  Follows,  is:  "To  throw  forward  in  parallel  rays  or 
straight  lines."  "Projection  means  either  the  act  or  the  result  of  pro- 
jecting parallel  rays  from  the  surface  of  a  body,  and  of  cutting  these 
rays  with  a  plane,  so  as  to  obtain  on  the  plane  a  shape,  corresponding 


Plane  A 


Plane  B 


'Projection   lines 


FIG.  i 8. 

point  for  point  with  that  of  the  body.     In  Mechanical  Drawing  these 
rays  are  called  projection  lines." 

Fig.  17  is  an  illustration  of  a  V  block  shown  in  perspective,  the 
end  view  of  the  block  being  projected  upon  the  plane.  Projection 
lines  are  thrown  out  from  the  points  or  corners  of  the  body,  and  the 


OF    THE 

UNIVERSITY 


LESSON    No.  12.— Continued. 


main  points  where  the  plane  intersects  these  lines  are  those  which  are 
used  in  developing  the  outline  of  this  body. 

This  perspective  is  used  simply  to  illustrate  the  principle  of  pro- 
jection, while  the  illustration  shown  in  Fig.  18  is  an  example  of  a 
mechanical  projection  of  the  same  block,  showing  the  three  views  in 
the  same  plane. 

Theoretically,  we  start  with  the  assumption  that  the  body  is  located 
directly  under  the  top  plane,  and  that  the  top  view  is  projected  up  to 
this  plane.  The  end  view  is  projected  upon  plane  A,  and  this  plane  is 
then  swung  up  parallel  with  the  plane  of  the  top  view.  The  same 
process  follows  for  the  side  view;  it  is  projected  upon  plane  B,  which 
is  swung  up  parallel  with  the  other  two  views,  all  of  the  views  now 
being  in  the  same  plane.  In  actual  practice,  the  draftsman  would  lay 
out  the  different  views  in  the  same  relation  to  each  other,  but  he  would 
simply  construct  the  views  by  means  of  his  T  square,  triangles,  and 
scale. 

As  an  aid  to  remember  true  projection,  and  in  order  to  enable  the 
student  to  ascertain  the  correctness  of  his  projection  drawings  regard- 
less of  the  manner  in  which  the  views  may  be  arranged,  the  following 
method  is  recommended. 

Observe  if  the  different  views  bear  the  same  relation  to  each  other 
as  those  shown  in  Fig.  18;  that  is,  that,  from  the  position  of  the  end 


view,  looking  toward  the  top  view,  one  will  see  what  has  been  drawn 
for  the  end  view,  and  from  the  position  of  the  side  view,  looking 
toward  the  top  view,  one  will  see  what  has  been  drawn  for  the  side 
view.  Furthermore,  from  the  position  of  the  top  view,  looking  toward 
the  end  view  and  side  view,  one  can  see  what  has  been  drawn  for  the 
top  view. 

THE  LESSON. — A  number  of  pieces  of  various  shapes  are  shown 
on  Drawing  C-ioc>7,  some  of  the  views  of  each  piece  being  incomplete. 
The  student  is  expected  to  lay  out  a  full-size  pencil  copy  of  this  draw- 
ing, with  all  of  the  views  properly  completed. 

To  finish  these  correctly  it  will  be  necessary  for  the  student  to  keep 
in  mind  what  has  been  written  above  in  regard  to  proving  that  the 
views  are  properly  projected. 

Do  this  work  neatly,  showing  all  necessary  hidden  lines,  but  remem- 
ber that  the  important  point  is  to  show  a  clear  understanding  of  simple 
projection. 

Place  all  dimensions  as  shown,  and  print  the  title  on  neatly.  Qual- 
ity, not  speed,  counts  at  present  in  all  this  work. 

In  Fig.  i,  view  C  is  complete;  finish  A  and  B. 

In  Fig.  2,  view  B  is  complete;  finish  A  and  C. 

In  Fig.  3,  view  C  is  complete;  finish  A  and  B. 

In  Fig.  4,  view  C  is  complete;  finish  A  and  B. 


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CLASS  Industrial  TRADE  Machinist 

John  W.Roberts  DATE  Sepf.  ^2.O7 


THE   CARNEGIE   TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL   DRAWING 


PROBLEMS  IN  PROJECTION 

SCALE  Full  Size  owa.  NO.  C.I 007 


OF   THE 

UNIVERSITY 

OF 


LESSON    No,  13. 


FLANGED  PULLEY.— The  figures  on  Drawing  C-ioo8  repre- 
ent  a  side  view  and  a  true  sectional  view  of  a  Flanged  Pulley. 

The  conventional  method  of  indicating  screw  threads  is  used  in  the 
holes  for  the  set  screws;  note  that  the  threads  appear  to  be  left  hand. 
These  threads  are  in  reality  right  hand,  and  it  is  desired  that  the  stu- 
dent shall  reason  out  for  himself  just  why  it  is  correct  to  show  the 
threads  in  this  manner. 

This  lesson  is  intended  to  give  the  student  a  clearer  conception  of 
the  subject  of  sectioning;  to  help  him  to  make  a  mental  picture  of 


what  the  pulley  looks  like  when  cut  in  half  along  the  vertical  center 
line.  Make  a  free-hand  sketch  of  the  pulley,  copying  carefully  all 
dimensions  and  necessary  information.  From  this  sketch  make  a 
full-size  pencil  drawing  of  the  pulley,  placing  all  dimensions  just  as 
shown  on  the  illustration. 

When  dimensioning  a  drawing,  bear  in  mind  that  your  drawing  is 
to  be  used  as  an  instrument  to  furnish  exact  information  to  some  one 
in  the  shop,  and  unless  you  do  your  work  carefully  and  accurately, 
costly  mistakes  may  be  the  result. 


Drill  £-Tapj  -2O  Thd. 
:.  Sef  Sc. 


ct/«ss   Industrial         T»/IOF  Machinist 
NAME  John  IV  Roberts  DATE:    Oct.  16-  O6. 


THE    CARNEGIE.    TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 
SCHOOL  OF   APPRENTICES    Atvo   JOURNEYMEN 

MECHANICAL     DRAWING 


FLANGED  PULLEY 

SCALE   Full  Size  DWG.Ne.C-/OO8 


LESSON    No.  14. 


HAND  WHEEL. — In  our  previous  lessons  on  sectioning  we  have 
dealt  with  true  sections,  while,  in  the  present  lesson,  the  sectional  view 
shown  of  the  Hand  Wheel  is  what  is  called  a  "conventional  section." 
In  other  words,  it  is  not  a  true  section,  but  a  special  one  which  is 
used  because  it  illustrates  the  shape  of  the  piece  more  clearly  for 
the  pattern  maker  and  machinist.  The  draftsman  can  lay  it  out 
more  easily  and  quickly  as  well — an  economy  that  should  be  con- 
sidered. 

As  an  illustration  of  the  convenience  of  special  sections,  note  the 
conventional  section  of  the  arm  of  the  hand  wheel;  without  this  section 
it  would  be  pretty  hard  to  give  the  pattern  maker  a  clear  idea  as  to  the 
shape  of  the  arm. 

This  conventional  method  of  sectioning  is  used  constantly  on  draw- 
ings of  such  pieces  as  wheels,  pulleys,  and  gears  with  arms. 


LESSON. — Make  a  full-size  pencil  drawing  of  the  Hand  Wheel. 

Place  all  dimensions  just  as  shown,  with  the  exception  of  those  that 
refer  to  the  handle;  these  dimensions  should  be  left  off,  as  they  were 
intended  merely  as  an  aid  to  the  student.  Mark  this  part  "No.  2 
Handle."  When  the  pencil  drawing  is  complete,  make  a  tracing  of  it. 
Try  to  do  this  work  neatly;  make  the  lines  of  the  tracing  clear  and  dis- 
tinct, keeping  in  mind  the  instructions  given  in  Lesson  No.  9. 

When  drawing  the  ball  of  the  handle, -do  not  try  to  make  the  two 
radii  (ij  and  i  inch)  touch,  as  they  should  be  joined  with  a  straight 
line.  The  student  should  bear  in  mind  that  where  radii  swinging  in 
opposite  directions  are  to  be  joined,  that  a  straight  line  should  be  used 
for  this  purpose,  otherwise  the  line  appears  to  have  a  corner  or  uneven 
place.  Where  the  radii  are  small,  as  at  the  stem  of  the  handle,  the 
rule  may  be  overlooked. 


CLASS     Indus fr/af         .TRADE   Machinist 
HAMC   <John  W.  Roberts.  DATE 


THE.    CARNEGIE    TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL  DRAWING 


8  HAND    WHEEL 

SCALE   full  Size  oiva.  NO.  C-IOO9 


LESSON 

DRAWING  TO  SCALE.— In  all  of  our  previous  lessons,  the 
pieces  illustrated  have  been  drawn  full  size;  in  our  present  lesson  we 
shall  take  up  the  subject  of  drawing  objects  smaller  than  full  size,  or 
"drawing  to  scale,"  as  it  is  generally  termed. 

In  most  modern  commercial  drafting  rooms,  the  drawings  are  made 
on  paper  of  certain  sizes.  These  standard  sizes  (usually  three  or  four) 
are  adopted  to  suit  the  needs  of  the  manufacturer,  and  each  of  the 
machine  parts  built  is  shown  on  one  of  these  standard -size -sheets. 

Small  parts  may  be  drawn  full  size,  but  large  ones  must,  of  necessity, 
be  drawn  to  a  smaller  scale,  as  J  size,  J  size,  and  J  size. 

These  are  the  scales  usually  adopted  by  manufacturers  of  machinery. 
The  piece  is  drawn  to  the  scale  necessary  for  clearness  and  best  suited 
to  one  of  the  standard-size  sheets,  while  the  dimensions  are  placed  in 
the  same  manner  as  if  the  piece  were  drawn  full  size.  In  other  words, 
the  dimensions  must  show  the  sizes  to  which  the  piece  is  to  be  finished 
in  the  shop. 

In  drawing  to  a  given  scale,  that  scale  becomes  our  unit  of  measure- 
ment. As  an  illustration,  take  our  present  lesson,  in  which  the  student 
is  expected  to  make  a  half-size  drawing  of  the  Lathe  Face  Plate. 

As  J  inch  is  our  unit  of  measurement,  J  inch  equals  i  inch,  but 
instead  of  dividing  each  dimension  by  two,  read  it  thus:  "if  halves 
for  if  inches,  5  halves  for  5  inches,  f  halves  for  f  inch,  etc." 

If  the  student  will  carefully  study  the  illustration  in  Fig.  19,  he 
will  observe  that  the  divisions  can  be  made  on  the  scale  by  simply 
training  the  eye  to  perform  this  operation. 

As  an  aid  in  readily  locating  a  dimension  on  the  scale,  look  for  the 
nearest  large  graduation ;  the  full-size  dimension  on  Fig.  19  is  sjf  inches, 
a  thirty-second  less  than  sf  inches,  which  figure  can  be  found  at  once. 
To  find  s||  inches  half  size,  look  for  sf  inches  half  size  and  point  back 
toward  zero  one-half  of  the  space  between  graduations.  To  locate 
SJ|  inches  quarter  size,  look  for  sf  inches  quarter  size  and  point  back 
toward  zero  one-fourth  of  the  space  between  graduations,  sff  inches 
one-eighth  size  is  located  in  the  same  manner. 


THE 
UNIVERSITY 


By  this  method  it  is  necessary  for  the  student  to  keep  but  one 
dimension  in  mind  when  making  a  division,  and  when  he  learns  to 
read  his  scale  properly,  he  is  much  less  liable  to  make  mistakes  than  if 
he  were  to  make  his  divisions  in  the  usual  way. 


Full  Size 


ones 


5&  halves 


"         j*  SH  quarters-^ 
\5geiffMhs 


|'i'|T|'iTi'|'iTr|'i'n'|'i'|'i'rn'  '[iTifi'pi1  Tri!r|T|'i'|T|'i  T'l'i'iTiTi  'I 

0 I I 


FIG.  19. 

To  get  a  radius  for  half-size  circles,  set  the  compasses  to  the  dimen- 
sion quarter  size.  For  example,  to  draw  the  end  view  of  the  hub  4-inch 
diameter  half  size,  take  a  radius  of  4  quarters. 

LESSON. — From  the  illustration,  make  a  half-size  pencil  drawing 
of  the  Lathe  Face  Plate. 

Section  AB  is  cut  along  the  line  AB,  and  is  a  conventional  method 
of  showing  a  true  section  along  this  line. 

Section  CD  is  necessary  to  give  the  pattern  maker  a  clear  idea  of 
the  shape  of-the  metal  back  of  the  T  slot. 

Where  dimensions  are  given  in  decimals,  draw  that  part  to  the  near- 
est sixty-fourth. 

Study  the  illustration  carefully,  so  as  to  get  a  clear  idea  of  the  mean- 
ing of  each  line.  Do  not  simply  copy;  try  to  make  a  mental  picture  of 
the  shape  of  the  piece. 

Use  the  edge  of  your  scale,  which  is  graduated  in  sixteenths,  and 
work  from  dimensions  given. 


Section  C~D 


Bore  2^034 
Tap  2/~  6  Thd. 

a  s.  stct. 


Section  A-B 


THE   CARNEGIE   TECHNICAL  SCHOOLS 


CLASS   Industrial  TRADE  Machinist 

HAHC  John  W,  Roberts  DATE  Oct.  2 O-  06. 


PITTSBURGH,  PA. 

SCHOOL  OF  APPRENTICES  ANO  J 

MECHANICAL    DRAWING 


LATHE  FACE:  PLATE: 


SCALE  j  Size 


owe.  NO.  C.IOIO 


LESSON    No.  16. 


ASSEMBLY  DRAWINGS.— It  is  common  practice  in  most 
drafting  rooms  to  make  drawings  which  show  several  details  of  a 
machine  fastened  together.  These  drawings  are  called  "assembly 
drawings,"  and  they  are  of  great  value  to  the  men  in  the  shop  who 
erect  or  assemble  the  machines.  They  are  very  necessary  also  when 
ordering  the  "stock"  or  materials  from  which  to  build  the  machines,  as 
the  "Bill  of  Material"  contains  all  the  necessary  information  for  this 
purpose. 

The  illustration  is  of  a  "Positive  Clutch  Coupling,"  so  called  from 
the  fact  that  the  motion  transmitted  by  this  coupling  is  positive,  there 
being  no  chance  for  one-half  to  slip  or  slide  over  the  other,  as  in  a 
coupling  where  one-half  turns  the  other  by  means  of  friction. 

The  stationary  half  is  keyed  tight  to  the  shaft  on  which  it  is  mounted. 
The  sliding  half,  which  is  on  a  separate  shaft,  is  fitted  in  such  a  manner 
as  to  slide  freely  lengthwise  on  the  shaft,  while  revolving  with  it. 

These  shafts  are  held  in  line  by  bearings,  one  shaft  being  tie 


"driver,"  the  other  the  "driven."  When  the  sliding  half  of  the  coup- 
ling is  moved  over  until  the  ends  of  the  halves  lock  together,  the  two 
shafts  revolve  as  one. 

The  end  view  of  the  stationary  half  shows  clearly  the  shape  of  the 
lugs  for  interlocking. 

Note  the  method  of  indicating  a  break  in  the  shaft;  this  method  is 
always  employed  to  indicate  a  break  in  a  round  piece  of  metal. 

LESSON. — Make  a  half-size  drawing  of  the  coupling. 

The  sizes  of  keys  may  be  obtained  from  the  "Bill  of  Material." 

When  laying  out  the  "Bill  of  Material,"  use  great  care  with  letters 
and  figures,  as  this  information  must  be  accurate  and  should  be  clearly 
shown. 

When  the  pencil  drawing  is  finished,  make  a  tracing  of  it;  the  lines 
of  the  tracing  should  be  fairly  heavy,  so  that  blue-prints  made  from  it 
will  show  the  figure  with  perfect  clearness. 


or  THE     Q 

UNIVERSITY 

OF 


Sliding  fit' 


•*'• 


1    r/~ 


Press  //'/ 


BILL  or  MATERIAL 


Item 
NO. 

Description  and  Material 

Pat.  No. 

Req. 

f  * 

© 

Stationary    Clutch  C.I. 

A  2O1 

I 

T* 

i 

Sliding   Clutch  C.I. 

ft 

1 

- 

$xje  x-SJ  Feather   Key  C.R. 

1 

1 

f"xjT*34"  Key   C.R. 

1 

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oj. 

7' 

-1"— 

"     IS    ' 

*"  '4-                                          3 

Industrial  TRAOC    Machinist 

John  W.  Roberts  OATC  Oct.  Pfi-  06. 


THE  CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGHt  'PA. 

SCHOOL  OF  APPRENTICES  AND  JOURNEYMEN 
MECHANICAL  DRAMMQ 


POSITIVE  CLUTCH  COUPLING 


SCALE  £  Size 


DWQ.   NO.  C-IQII 


OF   THE 

UNIVERSITY 


LESSON    No.  17. 


COUPLING. — The  assembly  drawing  used  for  the  present  lesson 
is  of  a  "  Compression  Shaft  Coupling." 

This  coupling  can  be  clamped  around  the  ends  of  two  shafts,  the 

.  ^       Across 

Across 

Corners 


Height  or 
Thickness 


Bolt  dia. 


X  Bolt  dia. 


FIG.  20. 


two  halves  of  the  coupling  being  held  together  by  means  of  the  bolts 
shown.  The  upper  half  of  the  coupling  is  fitted  with  a  key  which 
keeps  the  shafts  in  line. 

On  assembly  drawings  it  is  not  customary  to  give  the  dimensions  of 


pins,  screws,  bolts,  and  similar  details.  The  sizes  only  of  these  small 
parts  are  given,  so  that  they  can  be  ordered  from  the  storeroom,  where 
they  are  kept  in  stock. 

Most  modern  drafting  rooms  are  supplied  with  "Data  Books"  or 
sheets  of  stock  sizes,  from  which  the  draftsmen  obtain  all  necessary 
dimensions  of  these  small  details. 

No  dimensions  are  given  for  the  bolts  shown  in  the  present  lesson, 
but  the  student  may  obtain  the  size  of  bolt  and  nut  from  the  "Bill  of 
Material." 

From  the  following  data  the  student  is  expected  to  calculate  for 
himself  all  dimensions  necessary  to  draw  bolts  and  nuts  to  the  correct 
size. 

If  in  doubt  as  to  meaning  of  terms  given  below,  refer  to  illustration, 
Fig.  20. 

SIZES   OF  NUTS  AND  BOLT  HEADS. 

Sq.     nuts  or  bolt  heads  across  flats      =  ijxbolt  dia.  + J  inch. 

"     "    "        "         "      corners= dia.  across  flats  x"  1.414. 
Hex.     "     "    "       "         "      flats       =  i*X bolt  dia. +  i  inch. 

"     "    "       "         "      corners = dia.  across  flats X 1. 1 56. 
Height  or  thickness  of  nuts=bolt  diameter. 

"       "        "        "  bolt  heads=bolt  diameterX.So. 
"Length  of  Bolt"  always  refers  to  length  under  the  head.     Notice 
Drawing  C-iooi,  Lesson  No.  4. 

Make  a  half-size  pencil  drawing  of  the  coupling,  Drawing  C-ioi2. 
Remember  that  accuracy  and  neatness  are  points  of  great  import- 
ance. 

Make  a  tracing  of  the  finished  pencil  drawing. 


Ream  fit 


Section  A-B 


B/LL   or  MATERIAL 


Item 
No. 

Description  and  Ma  ferial 

Pat  No. 

^•9: 

(!) 

Half  Coup/ing   C.  1. 

A.  200 

/ 

1 

»«                           ff>                     »» 

.. 

/ 

® 

i*2£  M.B.Tap  Bo/f  nith  Nut 

6 

i 

f*i,'*/o'rer 

/ 

CLASS  Industrial  THADC  Machinist 

HAMC  John  W.Roberts          DAT,:   Oct.  20-O6. 


THE   CARNEGIE   TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  Of  APPRENTICES  AND  JOURNEYMEN 

MECHA  NtCAL    DP-*  WlfijQ 


COMPRESSION  SHAFT  COUPLING 


SCALE  £  Size 


Diva  NO.  C-IOI2 


LESSON    No.   18. 


PROJECTION. — Two  problems  in  projection  are  shown  on  Draw- 
ing C-IOI3- 

(a),  Fig.  i,  is  an  end  view  of  a  block  with  all  dimensions  shown. 
(6)  is  a  partly  finished  front  view,  showing  the  length  of  the  block. 

View  (a)  is  projected  upon  a  plane  which  is  set  at  an  angle  of  45°; 
this  plane  is  then  raised  to  a  vertical  position  and  swung  around  one- 
fourth  turn  or  90°,  so  as  to  show  the  front  view  (6). 

View  (r)  should  be  an  end  view  of  the  block  tilted  at  an  angle  of  45°. 

Lay  out  the  three  views  full  size,  finishing  them  completely  and 
placing  them  in  the  positions  indicated  on  the  drawing. 

Fig.  2  is  a  side  view  of  a  frustum  of  a  hexagonal  pyramid  with  the 
base  cut  away  at  an  angle  of  30°. 


The  small  end  or  top  of  frustum  is  ij  inches  across  flats,  and  the 
large  end  2  inches  across  flats  before  cutting  off  a  portion  of  the  base, 
as  shown  by  the  dotted  line. 

The  student  is  expected  to  lay  out  the  three  views  of  this  piece,  the 
top  and  end  views  to  be  placed  in  the  positions  indicated  on  the  draw- 
ing. 

Remember  that  this  lesson  is  intended  purely  as  a  study  in  pro- 
jection, and  do  this  work  very  carefully. 

If  the  student  fully  grasps  the  principles  of  projection,  he  will  have 
mastered  one  of  the  most  difficult  and  most  important  portions  of  the 
subject  of  mechanical  drawing. 

It  is  not  necessary  to  dimension  the  pencil  drawing. 


OF   THE 

UNIVERSITY 

OF 


P/ang 


Project  end  vien  here 
c 


F/g.2 


End  vieiv  here 


THE    CARNEGIE   TECHNICAL   SCHOOLS  PPOBLEMS  ,N  PROJECT/ON 


CLASS    Industrial  TRADE   Machinist 

HAME  John  W  Roberts  DATE  Oct.  10-  O7 


PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  J 

MECHANICAL    DRAWING 


SCALE    Full   Size  DWG    NO.C-IQ/3 


LESSON    No.  19. 


THE  ELLIPSE. — Make  a  neat  pencil  drawing  of  an  ellipse  by 
the  three  methods  indicated,  and  of  the  elliptical  curve  shown  on 
Drawing  0-1014. 

When  drawing  the  ellipse,  make  the  major  or  long  axis  3$  inches, 
and  the  minor  or  short  axis  2  inches  in  each  case. 

For  Fig.  i,  lay  off  the  major  and  minor  axes  to  the  lengths  given 
above;  take  a  straight  edge  made  of  any  suitable  material,  as  card- 
board or  wood,  and,  on  one  edge,  mark  off  the  points  AB  equal  to 
half  the  minor  axis;  from  A,  mark  off  point  C  equal  to  half  the  major 
axis.  Place  the  straight  edge  so  that  the  point  B  comes  on  the  major  axis 
and  point  C  on  the  minor  axis;  now,  with  the  pencil,  mark  a  point  on 
the  drawing  paper  at  A.  Shift  the  straight  edge  and  repeat  (keeping 
B  and  C  on  the  major  and  minor  axes  respectively),  placing  a  sufficient 
number  of  points  on  the  paper  to  enable  you  to  trace  a  curve  through 
them  easily. 


The  method  illustrated  in  Fig.  2  is  of  such  a  nature  that  the  student 
should  be  able  to  solve  the  problem  without  assistance. 

Fig.  3  is  known  as  the  "Three-radii  Method." 

Construct  the  rectangle  ADCEB.  Draw  the  diagonal  AC.  Through 
D,  draw  DF  at  right  angles  to  AC.  Then,  F  is  the  center  for  arc 
GCH,  and  J  is  the  center  for  arc  KAL. 

Make  OM=OC.     Describe  the  semicircle  AM. 

Make  OP=CN.  With  center  F,  describe  arc  RPS.  Make  AQ= 
ON.  Then,  with  J  as  center  and  radius  JQ,  describe  arc  intersecting 
arc  RPS  at  T.  T  is  the  center  for  the  tangent  arc  LG. 

To  construct  the  curve  shown  at  Fig.  4,  divide  the  base  lines  of 
the  curve  into  the  same  number  of  equal  parts  (any  number)  and  con- 
nect these  division  points  by  straight  lines.  The  combined  outer  sur- 
faces of  these  lines  form  the  desired  curve. 


Fig.  I 


N 


Fig.  3 


CLASS.    Industrial  TKAOC    Machinist 

W.  Rober+a  DXTc    Dec.  AS- 06 


THE   CARNEGIE    TECHNICAL   SCHOOLS 


H,  PA. 

SCHOOL  OF  APPRENTICES  AND  JOUBHCYMCH 
MCCHAHIQAL  DRAWING 


THE:   ELLIPSE 


SCALC  Full  Size  CHVG.M,.  CJOI4 


LESSON    No.  20. 


ENGINEERING  CURVES.— The  principle  of  this  lesson  is  to 
generate  the  path  oj  a  moi-ing  point.  The  curves  illustrated  are  con- 
stantly used  in  engineering  work,  and  a  knowledge  of  their  construction 
should  be  both  interesting  and  valuable  to  the  student. 

The  cycloid  is  the  curve  generated  by  a  point  on  the  circumference 
of  a  circle  when  rolled  along  a  straight  line.  When  the  generating 
circle  is  rolled  upon  another  circle,  an  epicycloid  will  be  generated. 

When  the  generating  circle  is  rolled  under  another  circle,  a  hypo- 
cycloid  will  be  generated. 

To  generate  the  cycloid  mechanically,  lay  off  the  base  and  center 
lines;  set  the  dividers  to  any  short  space  (so  that  the  length  of  the 
chord  is  about  equal  to  the  arc),  in  this  instance  \  inch,  ,and  step  off 
16  or  18  points  on  the  base  line.  Erect  perpendiculars  through  these 
points;  swing  in  the  generating  circle  from  these  different  points,  so  as 
to  place  the  circle  in  the  different  positions  which  it  would  assume  in 
making  one  complete  revolution.  Now,  with  the  dividers,  step  off  on 
the  second  circle  the  distance  it  has  rolled  along  the  base  line,  in  this 
ta>e  }  inch.  Repeat  for  each  new  position  of  the  generating  circle 
(measuring  with  the  dividers  the  distance  around  the  circle  that  it  has 
lolled  along  the  base  line),  until  a  complete  revolution  has  been  made, 
then  trace  the  curve  through  the  points  thus  found. 

The  epicycloid  and  hypocycloid  are  generated  in  the  same  manner, 


the  base  circle  replacing  the  base  line  of  the  cycloid. 

The  involute  is  the  curve  generated  by  every  point  in  a  cord  as  it 
is  wrapped  upon  or  unwound  from  a  cylinder. 

To  develop  the  involute  mechanically,  unwind  a  little  bit  of  the 
cord  at  a  time,  and  step  off  upon  the  line  the  distance  unwound. 

Set  the  dividers  to  \  inch  and  step  off  10  or  12  divisions  upon  the 
base  circle;  from  these  points  draw  tangent  lines  to  represent  the  cord 
in  different  positions  when  being  unwound. 

The  helix  or  screw  is  the  curve  which  would  be  generated  upon  a 
cylinder  revolved  at  a  constant  speed  against  a  point,  the  point  moving 
along  at  a  constant  speed  parallel  with  the  axis  of  the  cylinder. 

To  generate  this  curve  mechanically,  divide  the  circumference  of 
the  cylinder  into  any  number  of  equal  parts,  in  this  case  25,  numbering 
these  points  from  the  left  on  the  center  line,  as  shown.  Divide  the  pitch 
distance  on  the  cylinder  into  the  same  number  of  equal  spaces  (25)  by 
which  the  circumference  of  the  cylinder  was  divided. 

Now  locate  points  on  the  side  view  of  the  cylinder  at  the  intersec- 
tion of  the  vertical  division  lines  with  the  horizontal  projection  lines 
(these  lines  being  projected  from  the  points  on  the  end  view  of  the 
cylinder);  then  trace  the  curve  through  the  points  thus. formed.  This 
subject  requires  very  accurate  and  careful  work  on  the  part  of  the 
student. 


OF   THE 

UNIVERSITY 

OF 


Cycloid 


Involute 


Helix  or  Screw  .  P  Pitch 


CiAss  Industrial         TRAO£  Machinist 
NAME  John  W.Roberts       DATE  Feb.  6.07. 


THE   CARNEGIE   TECHNICAL  SCHOOLS 


f/TTSBUffSH,  PA. 

SCHOOL  Of  APPRENTICES  AND 

MECHANICAL   DRAWING 


ENGINEERING  CURVES 
THE  PATH  or  A  MOVING  POINT 


SCALC  full  Size 


DWS.ua.  C.IOIS 


I 


LESSON    No.  21. 


SPUR  GEAR.— From  Drawing  C-ioi6  make  a  full-size  pencil 
drawing  of  the  24-tooth  spur  gear  illustrated. 

The  student  should  study  carefully  the  following  memoranda,  as 
he  is  expected  to  make  use  of  them  in  obtaining  the  sizes  of  teeth, 
diameters  of  gear,  etc. 

If  grooves  are  cut  in  the  face  of  a  smooth  wheel,  the  parts  between 
the  grooves  are  called  lands.  A  part  added  to  a  land  is  called  an  ad- 
dendum. A  land  and  addendum  together  is  a  tooth.  Between  the 
teeth  are  spaces.  A  toothed  wheel  is  called  a  gear  wheel,  or  simply  a 
gear.  When  the  teeth  of  two  gears  e.ngage  together,  the  gears  are  said 
to  be  in  mesh.  Two  or  more  gears  in  mesh  are  called  a  train  of  gears. 
The  circumference  of  the  smooth  wheel  in  which  the  grooves  are  cut 
and  to  which  the  addenda  are  added  is  called  the  pitch  circle.  The 
teeth  of  meshing  gears  should  be  so  formed  that  their  pitch  circles  roll 
together  without  any  slip.  The  word  "diameter"  when  applied  to 
gears  is  understood  to  mean  the  pitch  diameter,  that  is,  the  diameter  of 
the  pitch  circle.  Diametral  pitch  of  a  gear  is  the  number  of  teeth  to 
each  inch  of  its  pitch  diameter.  Circular  pitch  is  the  distance  from 
the  center  of  one  tooth  to  the  center  of  the  next  tooth,  measured  along 
the  pitch  circle.  A  gear  blank  is  the  wheel  before  the  teeth  have  been 
cut  into  it. 

In  modern  practice  the  proportions  of  involute  cut  teeth  are  as 
follows:  The  tooth  thickness,  T,  is  equal  to  the  space,  S.  The  adden- 
dum, A,  is  equal  to  — .  _.  ,  ;  thus  for  4  pitch  the  addendum 

Diametral  Pitch 

is  \  inch.    The  clearance  is  generally  made  one-eighth  of  the  addendum 
height;  the  depth,  D,  is  equal  to  A,  with  clearance  added. 

The  radius,  R,  at  the  root  of  the  tooth  is  about  one-sixth  the  dis- 


tance B,  but  varies  greatly.     The  rim  thickness,  C,  is  usually  made 
approximately  equal  to  tooth  depth. 

USEFUL  GEAR  FORMULAS.— Circular  Pitch  or 
Diametral  Pitch  or  D.P.  =  3'I4I<5 


Pitch  Diameter= 


CP 

Number  of  teeth 
DP 


Distance  between  the  centers  of  two  gears  =$  of 


N+n 
DP' 


N=  number  of  teeth  in  large  gear;  n= number  of  teeth  in  small  gear. 

Outside  diameter  of  gear,  or  diameter  of  blank,  =  number  of  teeth 
in  gear+2-r-D.P. 

The  particular  involute  curve  most  generally  used  in  gear  teeth  is 
called  the  15°  involute.  To  construct  it:  Describe  the  pitch  circle  of 
the  required  gear  and  draw  a  line  tangent  to  it.  At  the  tangent  point, 
draw  a  line  at  an  angle  of  15°  to  the  tangent  line.  From  the  center  of 
pitch  circle,  draw  a  circle  tangent  to  the  15°  line;  this  is  called  the  base 
circle,  and  is  the  circle  upon  which  the  involute  is  generated. 

When  laying  out  the  gear  teeth,  observe  that  the  part  of  the  tooth 
inside  of  the  base  circle,  or  the  flank,  as  it  is  generally  termed,  is  a 
radial  line.  It  is  necessary  to  lay  out  the  involute  curve  but  once,  for 
the  student  may  set  his  compasses  to  a  radius  (which  will  be  an  approx- 
imation to  this  curve),  to  throw  in  the  faces  of  the  other  teeth.  This 
work  requires  the  utmost  care  to  obtain  accurate  results. 

When  pencil  drawing  is  complete,  make  a  good  clear  tracing. 

Where  the  dimensions  are  not  shown,  the  student  is  expected  to  use 
the  formulas  given  to  obtain  the  necessary  figures. 


True  Involute 


Addendum  Circle 

Pitch  Circle 
Base  Circle 
Poof  Circle 


CLASS  Industrial  TRADE  Machinist 

NAHIC  John  W.  Roberts          DATE  Mar.20.-O7. 


THE   CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH.  PA. 

SCHOOL  OF  APPRENTICES  AND  JOURNEYMEN 
MECHANICAL  DRAWING 


SPUR  GEAR 


SCALE  Full Size 


oiva.  NO.  C.  1016 


LESSON    No.  22. 


INTERSECTIONS.— The  important  principle  contained  in  this 
lesson  is  the  projection  of  a  point. 

From  Drawing  C-ioiy,  make  a  full-size  pencil  drawing  of  the 
intersecting  cylinders  and  their  developments. 

The  curve  formed  by  the  intersection  of  the  two  cylinders  is  found 
point  by  point  as  shown  by  points  2  and  4  on  the  illustration.  The 
oval  shown  in  the  end  view  is  formed  by  cutting  the  large  cylinder  off 
at  an  angle  of  30°  with  the  horizontal  plane;  it  is  found  in  the  same 
manner  as  the  curve  of  intersection. " 

If  the  student  studies  the  illustration  carefully,  he  should  be  able  to 
follow  out  the  method  of  projecting  a  point  from  one  view  to 
another. 

As  the  end  views  of  the  cylinders  are  the  only  views  on  which  the 
true  circumference  can  be  obtained,  it  naturally  follows  that  it  is  the 
end  view  in  each  case  that  should  be  used  to  locate  the  division  points. 

The  circumference  of  the  cylinder  may  be  divided  into  any  num- 
ber of  points,  and  those  points  projected  upon  the  other  views  to  obtain 
the  desired  curves. 


DEVELOPMENT.— The  student  should  try  to  realize  that  a  sur- 
face is  composed  of  a  series  of  lines. 

The  different  methods  of  developing  a  surface  are  usually  described 
by  the  kinds  of  'lines  used  for  this  purpose.  As  an  instance,  in  our 
present  lesson  we  use  parallel  lines  to  develop  the  surfaces  of  the 
cylinders. 

If  we  were  to  cut  the  large  cylinder  through  at  point  C,  and  were 
then  to  spread  it  out  flat,  we  would  have  a  duplicate  of  the' develop- 
ment of  the  large  cylinder  shown. 

For  the  reasons  given  above,  the  end  view  of  the  cylinder  is  the 
proper  place  to  obtain  the  true  length  of  the  development,  assuming 
that  the  student  is  unable  to  find  the  circumference  by  simple  arith- 
metic. 

The  lengths  of  the  various  lines  used  in  developing  the  surface  of 
the  pattern  may  be  obtained  from  the  side  view. 

It  is  very  desirable  that  each  student  should  make  a  careful  study 
of  this  subject,  as  a  thorough  knowledge  of  the  principle  involved  will 
be  of  value  when  drawing  difficult  shapes. 


OF   THE 

UNIVERSITY 

OF 
-IFQR^ 


I          S        3         4         5         6         7         a         S         10        II        IS 


c       d        e        f       g       h       j        k       m      n       a        b       c 


CLASS  Industrial        TRADE  Machinist 

NAME  John  W.Roberts       DATE  April  2O-O7. 


THE  CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH,  'PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL     DRAWING 


INTERSECTIONS  AND  DEVELOPMENTS 
PARALLEL  LINE  DEVELOPMENT 

SCALE  full  Size  DUG. NO.  C.I 017 


LESSON    No.  23. 


INTERSECTIONS.— From  Drawing  C-ioi8,  make  a  full-size 
pencil  drawing  of  the  intersecting  cone  and  cylinder  and  their  develop- 
ments. 

If  the  student  has  fully  mastered  the  previous  lesson  on  intersections, 
he  should  be  able  to  develop  the  curves  of  intersection  shown  in  the 
top  and  front  views  of  the  present  lesson.  These  curves  are  found  in 
the  same  manner  as  those  of  the  intersecting  cylinders;  that  is,  point 
by  point. 

The  student  may  divide  the  end  of  the  cylinder  into  any  number  of 
points,  then  draw  radial  lines  through  these  points.  Or  he  may  draw 
the  radial  lines  first,  and  then  place  points  at  the  intersections  of  the 
lines  with  the  end  of  the  cylinder,  as  shown  by  points  i  and  4. 

The  latter  method  is  the  one  used  in  the  illustration,  and  the  stu- 
dent should  observe  that  to  project  these  points  i  and  4,  it  is  first 
necessary  to  have  the  radial  line  1-4  projected  upon  the  top 
view. 


RADIAL-LINE  DEVELOPMENT.— In  our  last  lesson  the  sur- 
faces of  the  figures  were  composed  of  parallel  lines,  the  method  of 
development  being  named  from  the  kind  of  lines  used. 

In  our  present  lesson  we  find  it  necessary  to  use  radial  lines  to 
develop  the  surface  of  the  cone,  from  which  this  method  derives  the 
name  of  "Radial-line  Development." 

When  laying  out  the  development  of  the  cone,  the  student  must 
bear  in  mind  that  the  true  length  of  the  lines  on  the  cone  can  be  found 
on  the  sides  of  the  cone  only,  as  in  all  other  positions  the  lines  are  fore- 
shortened. Thus  to  get  the  true  distance  from  the  apex  of  the  cone 
to  point  i,  this  point  must  be  projected  to  one  of  the  sides. 

The  length  of  the  arc  of  the  development  is  equal  to  the  circum- 
ference of  the  base  of  the  cone. 

The  radial  lines  used  in  finding  the  intersections  are  also  used  in 
locating  the  opening  in  the  development. 

Do  your  work  very  carefully. 


THE   CARNEGIE   TECHNICAL  SCHOOLS 


CLASS  Industrial         TRADE  Machinist 

NAME  John  W.Roberts      DATE  April  26,07. 


PITTSBURGH.  PA 

or  APPRENTICES  AND 
MECHANICAL   DRAWING 


INTERSECTIONS  AND  DEVELOPMENTS 
RADIAL  LINE  DEVELOPMENT 


SCALE  Full  Size 


owe.  /vo.  C.  IO IB 


LESSON    No.  24. 


TRIANGULATION  DEVELOPMENT.— Upon  a  B-size  sheet 
of  drawing  paper  (i5"X22"),  make  a  full-size  pencil  drawing  of  the 
Transition  Piece  and  its  development. 

Sheet-metal  workers  require  a  great  many  patterns  which  cannot 
be  laid  out  to  good  advantage  by  either  the  Parallel-  or  Radial-line 
methods  of  development. 

These  patterns  may  usually  be  laid  out  by  dividing  the  surface  of 
the  figures  into  a  series  of  triangles,  from  which  this  method  gets  the 
name  "  Triangulation  Development." 


LESSON. — First  lay  out  the  two  views  of  the  piece  illustrated, 
marking  them  with  letters  and  figures  as  shown.  Then  find  the  true 
length  of  each  of  the  slope  lines  ABCD,  etc.  These  lengths  may  be 
found  in  the  manner  indicated  on  the  illustration,  which  the  student 
should  be  able  to  understand  without  help. 

Now,  using  these  lines  with  the  top  and  base  lines,  construct  the 
triangles  into  which  the  figure  had  been  previously  divided.  Connect 
these  triangles  in  the  manner  indicated  by  the  partial  development, 
and  the  result  will  be  the  complete  pattern  desired. 


b 


True  length 


CLA33  Industrial         TRADE:  Machinist 

John  W.Roberts       DATE  May  ff,O7. 


THE  CARNEGIE   TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL    DRAWING 


INTERSECTIONS  AND  DEVELOPMENTS 
TRIANCULATION  DEVELOPMENT 

SCALE  Pull  Size  OWG./VO.  i 


LESSON    No.  25. 


VALUE  OF  PRACTICE.— From  the  previous  lessons  the  stu- 
dent should  have  become  familiar  with  the  general  principles  of 
mechanical  drawing.  With  this  assumption  in  mind,  the  main 
requirement  of  the  student  is  now  to  obtain  sufficient  practice,  making 
detail  and  assembly  drawings,  to  help  him  to  become  proficient  in 
turning  out  rapidly  work  that  is  accurate,  with  the  lettering  and  dimen- 
sioning done  in  a  neat  and  attractive  manner. 

No  modern  drafting  room  will  send  out  blue  prints  of  drawings 
upon  which  the  lettering  has  been  poorly  done,  or  the  dimensions  of 
which  are  indistinct.  Many  a  young  draftsman  has  been  refused  em- 
ployment simply  because  he  was  a  poor  letterer.  If  the  applicant's 
sample  drawing  is  neatly  lettered  and  dimensioned,  the  chances  are 
that  he  will  be  given  an  opportunity  to  show  what  he  can  do. 

The  student  is  expected  to  do  the  very  best  work  he  is  capable  of, 
on  the  following  working  drawings. 

DETAIL  DRAWING.— The  present  lesson  is  a  quarter-size 
detail  drawing  of  the  lathe  leg  shown  on  Drawing  C-ioao.  Make  a 


tracing  of  the  finished  pencil  drawing. 

The  student  will  observe  that  the  metal  of  the  side  Of  the  leg  is 
J  inch  thick  near  the  back,  and  that  it  tapers  down  to  J  inch  at  the 
front  edge.  This  is  shown  in  the  top  view,  and  is  for  two  purposes: 
To  make  the  casting  light  but  strong,  and  also  to  allow  the  pattern  to 
be  easily  lifted  out  of  the  sand  when  making  molds  in  the  foundry. 

The  openings  in  the  back  of  the  leg  are  for  the  purpose  of  making 
the  casting  lighter.  The  J-inch  rib  around  these  openings  strengthens 
the  casting  without  adding  much  weight. 

To  throw  in  the  large  radii  given,  the  student  will  find  it  necessary 
to  use  a  beam  compass,  as  these  radii  are  too  long  for  the  ordinary 
compass,  even  though  the  extension  bar  were  used. 

In  most  drafting  rooms  a  mark  of  some  kind  is  used  on  the  draw- 
ings to  indicate  that  a  surface  is  to  be  finished,  that  is,  machined  in  the 
shop.  The  "finish  mark"  shown  on  the  present  lesson  is  adopted 
from  the  Universal  Dictionary  of  Mechanical  Drawing  by  Prof.  G. 
H.  Follows 


s~jg3to 


fj  Holes 

BILL  OF  MATERIAL 


Description  and  Mafer/al 


Paf.  No. 


7O 


Peq. 


is  Holes  in  -feet 
Section  A-B 


Industrial        TRADE  Machinist 
John  W.  Roberts      DATE:  May  fl-  07. 


THE:  CARNEGIE  TECHNICAL  SCHOOLS 


PITTSBURGH,  PA. 

SCHOOL.  Of  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL    OfAWIMG 


2  SPEED  LATHE 
LEG  DETAILS 


SCALE:  j-  Size 


Dwa.fJo.C-/OfO 


LESSON    No.  26. 


LATHE  BED.— Make  a  half-size  pencil  drawing  of  the  lathe  bed 
shown  on  drawing  C-iozi.  Make  a  tracing  of  the  finished  pencil 
drawing. 

This  drawing  shows  the  method  commonly  used  to  take  care  of 
pieces  which  are  too  large  for  standard-size  sheets;  this  method  is  to 
show  the  piece  "  broken, "  as  it  is  termed. 

The  lathe  bed  shown  is  five  feet  long,  and  to  show  it  without  "  break- 
ing," or  the  complete  bed,  would  necessitate  that  it  be  drawn  to  a  very 
small  scale,  so  small,  in  fact,  that  the  views  would  not  show  to  the  best 
advantage  what  the  drawing  was  intended  to  show. 

By  breaking  away  part  of  the  bed,  we  are  able  to  draw  it  to  a  larger 
scale  and  show  more  clearly  its  shape  and  size.  The  part  broken 
away  is  of  no  value  to  any  one  using  the  drawing,  as  it  is  similar  to  the 
rest  of  the  bed  adjoining  the  break. 


Observe  carefully  all  notes  and  dimensions,  and  see  that  none  are 
overlooked,  as  full  information  must  be  furnished  on  working  drawings. 

The  cap  screws  referred  to  in  the  "Bill  of  Material"  are  for  bolting 
the  legs  to  the  bed. 

The  broken  views  of  the  top  and  bottom  of  the  bed  are  intended 
to  show  more  clearly  the  shape  of  the  corners,  the  sizes  of  fillets,  and 
to  show  the  position  of  bolt  holes. 

The  student  should  refer  to  the  leg  drawing,  €-1020,  if  he  desires 
to  see  whether  the  positions  of  the  clearance  holes  in  the  top  view  of 
the  leg  correspond  to  the  tapped  holes  in  the  bottom  of  the  bed. 

Observe  the  method  of  using  the  "finish  mark"  shown  at  the  top 
of  the  end  view.  This  indicates  that  the  whole  surface  between  marks 
is  to  be  finished. 


Drill  g  dia^deep 
Tap  g-!6Thds. 


No. 

Description  and  Material 

Pat.  No. 

Req. 

S 

Bed    C.I. 

71 

I 

i 

ix/i'Hex.Hd.  Cap  Sc. 

a 

Industrial  TWXDC  Machinist 

NAME  John  W.Roberfs        DATC  May  10-07. 


THE   CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  ANO  JOURNEYMEN 

MECHANICAL     DRAWING 


12 


SCALE  75  Size 


LATHE: 
DETAILS 


OWG.HO.  C.I  OS  I 


LESSON    No.  27. 


TOOL-REST  DETAILS.  —  Most  of  the  parts  or  details  of  a 
speed-lathe  tool  rest  are  shown  on  Drawing  €-1022;  part  of  these 
details  are  drawn  half  size,  and  the  rest  full  size. 

Make  an  accurate  pencil  drawing  and  tracing  of  the  details  shown. 

The  hand  wheel  is  very  similar  to  one  drawn  in  an  earlier  lesson, 
with  the  exception  that  it  is  an  "offset"  wheel,  that  is,  the  rim  is  not 
central  over  the  arms,  but  set  to  one  side.  The  necessary  radii  with 
the  location  of  their  centers  are  shown,  so  that  the  student  should  be 


able  to  draw  this  hand  wheel  without  difficulty. 

When  drawing  the  arms  of  the  hand  wheel,  bear  in  mind  what  was 
said  in  the  earlier  hand-wheel  lesson,  in  regard  to  using  a  straight  line 
for  the  purpose  of  joining  two  curves. 

Do  not  overlook  any  of  the  dimensions  on  the  various  details,  for 
you  must  remember  that  you  are  furnishing  the  man  in  the  shop  with 
the  necessary  information  to  machine  these  parts  correctly. 

Use  great  care  with  the  lettering  and  figures. 


Finish  all  over- 


f?ivef 


Harden 


CLASS  Industrial  TffAOC  Machinist 

NAME  John  W.Roberts      DATE  Dec.  /cl.07. 


77VE  CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH    PA. 

SCHOOL  or  APPITENTICCS  AND  JOURNEYMEN 

MECHANICAL    DRAWING 


12  SPEED  LATHE: 
TOOL  REST  DETAILS 

&  Full  Size         owe.No.  C-/02e 


LESSON    No.  28. 


TOOL-REST  ASSEMBLY.— Drawing  €-1023  is  an  assembly 
drawing  of  the  complete  tool  rest. 

This  drawing  is  used  for  the  purpose  of  showing  how  the  different 
parts  are  fastened  together,  or  assembled,  as  it  is  termed. 

The  only  parts  dimensioned  are  the  stand  and  clamp,  all  of  the 
other  details  being  machined  from  Drawing  €-1022.  This  assembly 
drawing  is,  therefore,  used  as  a  detail  drawing  also,  as  the  stand  and 
clamp  may  be  machined  from  it. 


When  drawing  the  parts  that  are  not  dimensioned,  the  student  must 
necessarily  refer  to  the  detail  drawing  to  obtain  the  sizes  needed. 

Study  the  drawing  carefully  so  as  to  obtain  a  clear  understanding 
of  the  meaning  of  each  line.  Do  not  simply  copy  the  various  lines 
because  they  are  shown  on  the  original;  satisfy  yourself  as  to  their 
meaning. 

Think  for  yourself. 


J-  /" 

al 

r                                              /V"1 

' 

-.       X 

•'__   _^_^- 

N\fiw 


Drills-Tap  ^'-16  Thds. 


) 


BILL  or  MATERIAL 


Detail  of  Stand 


Hem 
No. 

Description  and  Material 

Pat.  No. 

Req. 

(JJ 

Tool  Rest.  C.I. 

79 

1 

® 

-     Stand,  C.  1. 

80 

I 

1 

•     Base,  C.I. 

81 

1 

® 

-   Hand  Wheel,  C.I. 

82 

1 

i 

••    Clamp,  W.  1. 

1 

i 

Clamp  Bolt,  W.  1. 

1 

© 

Adjusting  Screw,  C.R. 

1 

r  ® 

Adj.  Screw  Lever,  C.R. 

1 

CLASS  Industrial  TRADE  Machinist 

f 
John  W. Roberts         r>ATc  Dec.P4.O7. 


THE  CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL     D£?4WfNG 


/<?  SPEED  LATHE. 
TOOL  REST  A  SSEMBLY 


SCALC  ->5  Size 


OIVG.  NO.  C.  IO2-3 


LESSON    No.  29. 


TAILSTOCK  DETAILS.— Part  of  the  details  of  a  lathe  tailstock 
are  shown  on  Drawing  €-1024. 

The  sectional  view  of  the  spindle  shows  the  taper  bore  in  one  end, 
and  the  method  of  fastening  the  bronze  nut  in  the  other  end. 

The  end  of  the  spindle  is  bored  to  a  taper  of  f  inch  per  foot,  or  the 
"Morse  Taper,"  a  name  by  which  this  particular  taper  is  known  in 
shops  and  drafting  rooms.  By  a  taper  of  f  inch  per  foot,  we  mean 
that  a  cylindrical  piece  12  inches  long  and  i  inch  in  diameter  at  the 
small  end  will  be  if  inches  in  diameter  at  the  large  end.  In  other 


words,  the  piece  is  f  inch  larger  in  diameter  at  one  end  than  at  the 
other. 

By  this  time  the  student  should  be  sufficiently  familiar  with  hand 
wheels  to  need  no  instruction  on  this  subject. 

The  binding  screw  shown  is  an  illustration  which  shows  the  value 
of  a  knowledge  of  shop  practice.  This  screw  is  machined  in  a  lathe 
in  the  manner  shown  by  the  solid  lines;  after  being  finished,  it  is  placed 
in  a  special  forming  tool,  where  it  is  bent  to  the  shape  shown  by  the 
dash  lines.  Make  a  tracing  of  the  finished  pencil  drawing. 


Not?  Morse  Taper 


•• 


'.  per  'in. 


Ci/<ss  Industrial         TRADE  Machinist 
NAME  John  W.Roberts        DATE  Dec.  JO- 07. 


THE  CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH.  PA. 

SCHOOL  OF  APPRZNTICES  AND  JOURNEYMEN 
MECHANICAL  DRAWING 


IS  SPEED  LATHE 
TAILSTOCK  DETAILS 

SCALE  full  Size  owa.  «o.  C_  IOS4 


LESSON    No.  30. 


TAILSTOCK  DETAILS.— The  rest  of  the  details  of  the  lathe 
tailstock  are  shown  on  Drawing  0-1025. 

The  small  spindle  key  is  used  to  prevent  the  spindle  from  revolving. 

The  square-thread  screw  is  used  to  move  the  spindle  in  and  out  of 
the  tailstock  barrel.  The  manner  in  which  the  thread  is  shown  on 
this  screw  indicates  that  it  is  to  be  cut  the  full  length  to  the  collar. 
The  main  object  in  showing  the  thread  in  this  manner  is  to  save  the 
draftsman's  time. 

The  small  key  set  into  the  stem  of  the  screw  is  known  as  a  Wood- 
ruff key.  This  key  resembles  a  portion  of  a  washer  driven  into  a  slot 


milled  in  the  screw. 

From  the  rules  given  in  a  previous  lesson,  the  student  can  obtain 
the  dimensions  necessary  to  draw  the  hexagon  nut. 

The  wrench  shown  is  used  to  tighten  the  nut  on  the  clamp  bolt, 
thus  fastening  the  tailstock  to  the  bed. 

The  tailstock  plug,  or  bell,  as  it  is  usually  termed,  supports  the 
spindle  screw. 

The  small  steel  oiler  is  used  to  drop  oil  on  the  centers.  Make  a 
pencil  drawing  and  tracing  of  this  lesson.  Do  the  very  best  work  you 
are  capable  of. 


°F    i 

UNIVERSITY 


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to 


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1 

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W- 


/ 
/6  Thd.per  in. 

r* 


i_r±^ 


t    * 


CLASS  Industrial  T/TADC  Machinist 

NAME  John  W.ffoberfs         OATC  Jan.  6- OB. 


THE  CARNEGIE  TECHNICAL  SCHOOLS 


QH,  PA. 
SCHOOL  or  APPRENTICES  AND  J 

MECHANICAL.     &PAWM 


//?  SPEED  LATHE: 
TAILSTOCK  DETAILS 


SCALC  rull  Size 


DWB.No.  C-1025 


LESSON    No.  31, 


TAILSTOCK  ASSEMBLY.  —  Drawing  €-1026  shows  the  tail- 
stock  completely  assembled,  with  all  the  details  numbered  to  corre- 
spond with  the  numbers  in  the  "Bill  of  Material." 

Where  dimensions  are  not  shown  on  certain  parts,  the  student  is 
expected  to  refer  to  the  detail  drawings  for  the  necessary  informa- 
tion. 

The  saw  cut  on  the  side  of  the  tailstock  barrel  is  for  the  purpose  of 


allowing  this  part  to  clamp  tightly  around  the  spindle  when  the  bind- 
ing screw  is  tightened  down. 

The  oil  hole  shown  in  the  bell  should  be  drilled  after  it  is  in  place 
in  the  barrel,  as  it  should  of  necessity  be  on  the  upper  side  of  the  bell. 

Make  this  drawing  and  tracing  very  carefully;  do  not  overlook  any 
dimensions  or  notes.  Bear  in  mind  that  nothing  is  good  enough  but 
the  best  work  you  are  able  to  do. 


••**--;-=  -p*  *  =  =.-»=i--r-_-s.-=.i.-fs.-B.= --^a-^»«  s.-s.*«^i 


hole 


Bore  l£  Tap  I$-I2  Thd. 


BILL  or  MATERIAL 


Note:  For  details  see    Dwgs.  CJO24  &  C./OP5 


//<?//? 

A/o. 

Description  and  Material 

Pat.  No. 

Req. 

s 

Tailstock,  C.I. 

76 

I 

1 

Spindle,  Corona  Steel 

1 

i 

Screw  C.R.  with  j'Hex.  Nut. 

/ 

i 

Bell,   C.I. 

77 

I 

i 

Hand  Wheel.  C.  1. 

78 

1 

i 

Dead  Center,  Tool  Steel 

1 

a 

Spindle  Nut,  Bz. 

1 

$ 

£X?  Woodruff  Key,  C.R. 

1 

| 

/}  Washer,  C.f?. 

1 

@ 

,fXitxj?  Spindle  Key,  C.R. 

1 

® 

Oiler.  C.R. 

1 

i 

Binding  Screw,  C.R. 

1 

1 

f~X6  Clamp  Bolt  with  Hex.Nut 

1 

s 

Clamp  ,  W.  1. 

I 

CLASS  Industrial         T/MOC  Machinist 
HAMcJohn  W. Roberts          DATE  Jan. I £- 


THE  CARNEGIE  TECHNICAL  SCHOOLS 

PITTSBURGH,  PA. 

SCHOOL  or  APPRENTICES  AND  JOURNEYMEN 

MECHANICAL     DRAWING 


12  SPEED  LATHE 
TAILSTOCK  ASSEMBLY 


Size 


owe.  NO.  C.I026 


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Barber,  T.  W.— The  Engineers'  Sketch  Book  of  Mechanical  Move- 
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Davidson,  K.  A. — Drawing  for  Machinists  and  Engineers.  Compris- 
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Fox,  Wm.  and  Chas.  W.  Thomas.— A  Practical  Course  in  Mechan- 
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Heather,  J.  F. — Mathematical  Instruments;  their  Construction,  Ad- 
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